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File _service:download_url:1441.patch of Package mutter (Revision 11a78eae7a78b4269c2a4fff2b4d81be)

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From 3f25161ea27f7b3144208db08df94f098d2a1db7 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 17 Sep 2021 17:48:20 +0800
Subject: [PATCH 01/31] cogl/onscreen: Add function
 cogl_onscreen_count_pending_frames

---
 cogl/cogl/cogl-onscreen-private.h | 3 +++
 cogl/cogl/cogl-onscreen.c         | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/cogl/cogl/cogl-onscreen-private.h b/cogl/cogl/cogl-onscreen-private.h
index 959a60533b3..785f67aca16 100644
--- a/cogl/cogl/cogl-onscreen-private.h
+++ b/cogl/cogl/cogl-onscreen-private.h
@@ -79,3 +79,6 @@ cogl_onscreen_peek_tail_frame_info (CoglOnscreen *onscreen);
 
 COGL_EXPORT CoglFrameInfo *
 cogl_onscreen_pop_head_frame_info (CoglOnscreen *onscreen);
+
+COGL_EXPORT unsigned int
+cogl_onscreen_count_pending_frames (CoglOnscreen *onscreen);
diff --git a/cogl/cogl/cogl-onscreen.c b/cogl/cogl/cogl-onscreen.c
index 09849607b8d..09428591f06 100644
--- a/cogl/cogl/cogl-onscreen.c
+++ b/cogl/cogl/cogl-onscreen.c
@@ -511,6 +511,14 @@ cogl_onscreen_pop_head_frame_info (CoglOnscreen *onscreen)
   return g_queue_pop_head (&priv->pending_frame_infos);
 }
 
+unsigned int
+cogl_onscreen_count_pending_frames (CoglOnscreen *onscreen)
+{
+  CoglOnscreenPrivate *priv = cogl_onscreen_get_instance_private (onscreen);
+
+  return g_queue_get_length (&priv->pending_frame_infos);
+}
+
 CoglFrameClosure *
 cogl_onscreen_add_frame_callback (CoglOnscreen *onscreen,
                                   CoglFrameCallback callback,
-- 
GitLab

From cd13794d5a5e37c4a673c2655dab9fb31e267029 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Mon, 12 Feb 2024 17:16:03 +0800
Subject: [PATCH 02/31] cogl/onscreen: Indent declaration parameters to align
 with above/below

This fixes warnings from check-code-style.
---
 cogl/cogl/cogl-onscreen-private.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cogl/cogl/cogl-onscreen-private.h b/cogl/cogl/cogl-onscreen-private.h
index 785f67aca16..86d8ea2d5ff 100644
--- a/cogl/cogl/cogl-onscreen-private.h
+++ b/cogl/cogl/cogl-onscreen-private.h
@@ -78,7 +78,7 @@ COGL_EXPORT CoglFrameInfo *
 cogl_onscreen_peek_tail_frame_info (CoglOnscreen *onscreen);
 
 COGL_EXPORT CoglFrameInfo *
-cogl_onscreen_pop_head_frame_info (CoglOnscreen *onscreen);
+cogl_onscreen_pop_head_frame_info  (CoglOnscreen *onscreen);
 
 COGL_EXPORT unsigned int
 cogl_onscreen_count_pending_frames (CoglOnscreen *onscreen);
-- 
GitLab

From 4af18a35cdc565777db5aa1be5d28d851c5db963 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 20 Apr 2022 18:33:43 +0800
Subject: [PATCH 03/31] kms: Keep a shutting_down flag

---
 src/backends/native/meta-kms.c | 9 +++++++++
 src/backends/native/meta-kms.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/src/backends/native/meta-kms.c b/src/backends/native/meta-kms.c
index d41fcefb5a6..4809ca0593d 100644
--- a/src/backends/native/meta-kms.c
+++ b/src/backends/native/meta-kms.c
@@ -63,6 +63,8 @@ struct _MetaKms
   int kernel_thread_inhibit_count;
 
   MetaKmsCursorManager *cursor_manager;
+
+  gboolean shutting_down;
 };
 
 G_DEFINE_TYPE (MetaKms, meta_kms, META_TYPE_THREAD)
@@ -354,6 +356,7 @@ static void
 on_prepare_shutdown (MetaBackend *backend,
                      MetaKms     *kms)
 {
+  kms->shutting_down = TRUE;
   meta_kms_run_impl_task_sync (kms, prepare_shutdown_in_impl, NULL, NULL);
   meta_thread_flush_callbacks (META_THREAD (kms));
 
@@ -413,6 +416,12 @@ meta_kms_new (MetaBackend   *backend,
   return kms;
 }
 
+gboolean
+meta_kms_is_shutting_down (MetaKms *kms)
+{
+  return kms->shutting_down;
+}
+
 static void
 meta_kms_finalize (GObject *object)
 {
diff --git a/src/backends/native/meta-kms.h b/src/backends/native/meta-kms.h
index 74340140639..f6b19520bec 100644
--- a/src/backends/native/meta-kms.h
+++ b/src/backends/native/meta-kms.h
@@ -60,6 +60,8 @@ MetaKmsDevice * meta_kms_create_device (MetaKms            *kms,
                                         MetaKmsDeviceFlag   flags,
                                         GError            **error);
 
+gboolean meta_kms_is_shutting_down (MetaKms *kms);
+
 MetaKms * meta_kms_new (MetaBackend   *backend,
                         MetaKmsFlags   flags,
                         GError       **error);
-- 
GitLab

From 06c9493b5122ba88742475c1084a2642948bb904 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 26 Oct 2021 18:50:50 +0800
Subject: [PATCH 04/31] renderer/native: Avoid requeuing the same onscreen for
 a power save flip

This is a case that triple buffering will encounter. We don't want it
to queue the same onscreen multiple times because that would represent
multiple flips occurring simultaneously.

It's a linear search but the list length is typically only 1 or 2 so
no need for anything fancier yet.
---
 src/backends/native/meta-renderer-native.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backends/native/meta-renderer-native.c b/src/backends/native/meta-renderer-native.c
index aa76d018ca2..770b5ab755c 100644
--- a/src/backends/native/meta-renderer-native.c
+++ b/src/backends/native/meta-renderer-native.c
@@ -748,6 +748,9 @@ meta_renderer_native_queue_power_save_page_flip (MetaRendererNative *renderer_na
 {
   const unsigned int timeout_ms = 100;
 
+  if (g_list_find (renderer_native->power_save_page_flip_onscreens, onscreen))
+    return;
+
   if (!renderer_native->power_save_page_flip_source_id)
     {
       renderer_native->power_save_page_flip_source_id =
-- 
GitLab

From b55e7db38db4f759f96de9ddfe618a08c37365b1 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Mon, 1 Nov 2021 19:35:34 +0800
Subject: [PATCH 05/31] renderer/native: Steal the power save flip list before
 iterating over it

Because a single iteration might also grow the list again.
---
 src/backends/native/meta-renderer-native.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/backends/native/meta-renderer-native.c b/src/backends/native/meta-renderer-native.c
index 770b5ab755c..601fd674a49 100644
--- a/src/backends/native/meta-renderer-native.c
+++ b/src/backends/native/meta-renderer-native.c
@@ -731,12 +731,18 @@ static gboolean
 dummy_power_save_page_flip_cb (gpointer user_data)
 {
   MetaRendererNative *renderer_native = user_data;
+  GList *old_list =
+    g_steal_pointer (&renderer_native->power_save_page_flip_onscreens);
 
-  g_list_foreach (renderer_native->power_save_page_flip_onscreens,
+  g_list_foreach (old_list,
                   (GFunc) meta_onscreen_native_dummy_power_save_page_flip,
                   NULL);
-  g_clear_list (&renderer_native->power_save_page_flip_onscreens,
+  g_clear_list (&old_list,
                 g_object_unref);
+
+  if (renderer_native->power_save_page_flip_onscreens != NULL)
+    return G_SOURCE_CONTINUE;
+
   renderer_native->power_save_page_flip_source_id = 0;
 
   return G_SOURCE_REMOVE;
-- 
GitLab

From 570f7e1be6391251e837d0607c47504eda5d89fa Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 10 Dec 2021 16:40:58 +0800
Subject: [PATCH 06/31] onscreen/native: Log swapbuffers and N-buffering when
 MUTTER_DEBUG=kms

---
 src/backends/native/meta-onscreen-native.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 1a31f04a164..2b57731be63 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1305,6 +1305,19 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   COGL_TRACE_BEGIN_SCOPED (MetaRendererNativeSwapBuffers,
                            "Meta::OnscreenNative::swap_buffers_with_damage()");
 
+  if (meta_is_topic_enabled (META_DEBUG_KMS))
+    {
+      unsigned int frames_pending =
+        cogl_onscreen_count_pending_frames (onscreen);
+
+      meta_topic (META_DEBUG_KMS,
+                  "Swap buffers: %u frames pending (%s-buffering)",
+                  frames_pending,
+                  frames_pending == 1 ? "double" :
+                  frames_pending == 2 ? "triple" :
+                  "?");
+    }
+
   secondary_gpu_fb =
     update_secondary_gpu_state_pre_swap_buffers (onscreen,
                                                  rectangles,
-- 
GitLab

From 532baeaaa7dd3db2a40933e3e3b5ab4e064d6047 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 28 Jul 2021 16:35:56 +0800
Subject: [PATCH 07/31] onscreen/native: Replace an assertion that double
 buffering is the maximum

Because it soon won't be the maximum. But we do want to verify that the
frame info queue is not empty, to avoid NULL dereferencing and catch logic
errors.
---
 src/backends/native/meta-onscreen-native.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 2b57731be63..dbc503ebf15 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -207,7 +207,7 @@ meta_onscreen_native_notify_frame_complete (CoglOnscreen *onscreen)
 
   info = cogl_onscreen_pop_head_frame_info (onscreen);
 
-  g_assert (!cogl_onscreen_peek_head_frame_info (onscreen));
+  g_return_if_fail (info);
 
   _cogl_onscreen_notify_frame_sync (onscreen, info);
   _cogl_onscreen_notify_complete (onscreen, info);
-- 
GitLab

From 0201e5f0d803d352e0e57123b8fc9728c246d0e5 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 16 Sep 2021 16:26:25 +0800
Subject: [PATCH 08/31] onscreen/native: Deduplicate calls to
 clutter_frame_set_result

All paths out of `meta_onscreen_native_swap_buffers_with_damage` from
here onward would set the same `CLUTTER_FRAME_RESULT_PENDING_PRESENTED`
(or terminate with `g_assert_not_reached`).

Even failed posts set this result because they will do a
`meta_onscreen_native_notify_frame_complete` in
`page_flip_feedback_discarded`.
---
 src/backends/native/meta-onscreen-native.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index dbc503ebf15..06f9e81e8d7 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1417,6 +1417,9 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
 #endif
     }
 
+  clutter_frame_set_result (frame,
+                            CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
+
   /*
    * If we changed EGL context, cogl will have the wrong idea about what is
    * current, making it fail to set it when it needs to. Avoid that by making
@@ -1453,8 +1456,6 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
     {
       meta_renderer_native_queue_power_save_page_flip (renderer_native,
                                                        onscreen);
-      clutter_frame_set_result (frame,
-                                CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
       return;
     }
 
@@ -1474,8 +1475,6 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
           kms_update = meta_frame_native_steal_kms_update (frame_native);
           meta_renderer_native_queue_mode_set_update (renderer_native,
                                                       kms_update);
-          clutter_frame_set_result (frame,
-                                    CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
           return;
         }
       else if (meta_renderer_native_has_pending_mode_set (renderer_native))
@@ -1489,8 +1488,6 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
 
           meta_frame_native_steal_kms_update (frame_native);
           meta_renderer_native_post_mode_set_updates (renderer_native);
-          clutter_frame_set_result (frame,
-                                    CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
           return;
         }
       break;
@@ -1506,8 +1503,6 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
                                                       kms_update);
 
           meta_renderer_native_post_mode_set_updates (renderer_native);
-          clutter_frame_set_result (frame,
-                                    CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
           return;
         }
       break;
@@ -1522,7 +1517,6 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   kms_update = meta_frame_native_steal_kms_update (frame_native);
   meta_kms_device_post_update (kms_device, kms_update,
                                META_KMS_UPDATE_FLAG_NONE);
-  clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
 }
 
 gboolean
-- 
GitLab

From 8be2fb615295a6c3d378db84a3b92d77ec1520c6 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 28 Jul 2021 16:29:27 +0800
Subject: [PATCH 09/31] onscreen/native: Split swap_buffers_with_damage into
 two functions

1. The EGL part: meta_onscreen_native_swap_buffers_with_damage
2. The KMS part: post_latest_swap
---
 src/backends/native/meta-onscreen-native.c | 66 +++++++++++++++++-----
 1 file changed, 53 insertions(+), 13 deletions(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 06f9e81e8d7..524bc393d5d 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -125,6 +125,12 @@ struct _MetaOnscreenNative
   gulong privacy_screen_changed_handler_id;
   gulong color_space_changed_handler_id;
   gulong hdr_metadata_changed_handler_id;
+
+  struct {
+    int *rectangles;  /* 4 x n_rectangles */
+    int n_rectangles;
+    ClutterFrame *frame;
+  } next_post;
 };
 
 G_DEFINE_TYPE (MetaOnscreenNative, meta_onscreen_native,
@@ -132,6 +138,9 @@ G_DEFINE_TYPE (MetaOnscreenNative, meta_onscreen_native,
 
 static GQuark blit_source_quark = 0;
 
+static void
+post_latest_swap (CoglOnscreen *onscreen);
+
 static gboolean
 init_secondary_gpu_state (MetaRendererNative  *renderer_native,
                           CoglOnscreen        *onscreen,
@@ -1279,28 +1288,20 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   CoglRendererEGL *cogl_renderer_egl = cogl_renderer->winsys;
   MetaRendererNativeGpuData *renderer_gpu_data = cogl_renderer_egl->platform;
   MetaRendererNative *renderer_native = renderer_gpu_data->renderer_native;
-  MetaRenderer *renderer = META_RENDERER (renderer_native);
-  MetaBackend *backend = meta_renderer_get_backend (renderer);
-  MetaMonitorManager *monitor_manager =
-    meta_backend_get_monitor_manager (backend);
   MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
   MetaOnscreenNativeSecondaryGpuState *secondary_gpu_state;
   MetaGpuKms *render_gpu = onscreen_native->render_gpu;
   MetaDeviceFile *render_device_file;
   ClutterFrame *frame = user_data;
-  MetaFrameNative *frame_native = meta_frame_native_from_frame (frame);
-  MetaKmsUpdate *kms_update;
   CoglOnscreenClass *parent_class;
   gboolean create_timestamp_query = TRUE;
   gboolean egl_context_changed = FALSE;
-  MetaPowerSave power_save_mode;
   g_autoptr (GError) error = NULL;
   MetaDrmBufferFlags buffer_flags;
   MetaDrmBufferGbm *buffer_gbm;
   g_autoptr (MetaDrmBuffer) primary_gpu_fb = NULL;
   g_autoptr (MetaDrmBuffer) secondary_gpu_fb = NULL;
-  MetaKmsCrtc *kms_crtc;
-  MetaKmsDevice *kms_device;
+  size_t rectangles_size;
 
   COGL_TRACE_BEGIN_SCOPED (MetaRendererNativeSwapBuffers,
                            "Meta::OnscreenNative::swap_buffers_with_damage()");
@@ -1429,12 +1430,47 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   if (egl_context_changed)
     _cogl_winsys_egl_ensure_current (cogl_display);
 
-  kms_crtc = meta_crtc_kms_get_kms_crtc (META_CRTC_KMS (onscreen_native->crtc));
-  kms_device = meta_kms_crtc_get_device (kms_crtc);
+  rectangles_size = n_rectangles * 4 * sizeof (int);
+  onscreen_native->next_post.rectangles =
+    g_realloc (onscreen_native->next_post.rectangles, rectangles_size);
+  memcpy (onscreen_native->next_post.rectangles, rectangles, rectangles_size);
+  onscreen_native->next_post.n_rectangles = n_rectangles;
+
+  g_clear_pointer (&onscreen_native->next_post.frame, clutter_frame_unref);
+  onscreen_native->next_post.frame = clutter_frame_ref (frame);
+
+  post_latest_swap (onscreen);
+}
+
+static void
+post_latest_swap (CoglOnscreen *onscreen)
+{
+  CoglFramebuffer *framebuffer = COGL_FRAMEBUFFER (onscreen);
+  CoglContext *cogl_context = cogl_framebuffer_get_context (framebuffer);
+  CoglRenderer *cogl_renderer = cogl_context->display->renderer;
+  CoglRendererEGL *cogl_renderer_egl = cogl_renderer->winsys;
+  MetaRendererNativeGpuData *renderer_gpu_data = cogl_renderer_egl->platform;
+  MetaRendererNative *renderer_native = renderer_gpu_data->renderer_native;
+  MetaRenderer *renderer = META_RENDERER (renderer_native);
+  MetaBackend *backend = meta_renderer_get_backend (renderer);
+  MetaMonitorManager *monitor_manager =
+    meta_backend_get_monitor_manager (backend);
+  MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
+  MetaPowerSave power_save_mode;
+  MetaCrtcKms *crtc_kms = META_CRTC_KMS (onscreen_native->crtc);
+  MetaKmsCrtc *kms_crtc = meta_crtc_kms_get_kms_crtc (crtc_kms);
+  MetaKmsDevice *kms_device = meta_kms_crtc_get_device (kms_crtc);
+  MetaKmsUpdate *kms_update;
+  g_autoptr (MetaKmsFeedback) kms_feedback = NULL;
+  g_autoptr (ClutterFrame) frame =
+    g_steal_pointer (&onscreen_native->next_post.frame);
+  MetaFrameNative *frame_native;
 
   power_save_mode = meta_monitor_manager_get_power_save_mode (monitor_manager);
   if (power_save_mode == META_POWER_SAVE_ON)
     {
+      frame_native = meta_frame_native_from_frame (frame);
+
       kms_update = meta_frame_native_ensure_kms_update (frame_native,
                                                         kms_device);
       meta_kms_update_add_result_listener (kms_update,
@@ -1449,8 +1485,8 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
                                       onscreen_native->crtc,
                                       kms_update,
                                       META_KMS_ASSIGN_PLANE_FLAG_NONE,
-                                      rectangles,
-                                      n_rectangles);
+                                      onscreen_native->next_post.rectangles,
+                                      onscreen_native->next_post.n_rectangles);
     }
   else
     {
@@ -2872,6 +2908,10 @@ meta_onscreen_native_dispose (GObject *object)
 
   g_clear_object (&onscreen_native->output);
   g_clear_object (&onscreen_native->crtc);
+
+  g_clear_pointer (&onscreen_native->next_post.rectangles, g_free);
+  g_clear_pointer (&onscreen_native->next_post.frame, clutter_frame_unref);
+  onscreen_native->next_post.n_rectangles = 0;
 }
 
 static void
-- 
GitLab

From 029c0f632ea1f9e0348bf5effe7d021ea990d432 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 28 Oct 2021 17:24:11 +0800
Subject: [PATCH 10/31] onscreen/native: Add a missing frame notification

In the unlikely event that swap_buffers_with_damage drops the previous swap
it was forgetting to notify about the discarded frame. That could lead to
frame clock freezes.
---
 src/backends/native/meta-onscreen-native.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 524bc393d5d..eaa00d45a86 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1394,6 +1394,15 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
     {
     case META_RENDERER_NATIVE_MODE_GBM:
       g_warn_if_fail (onscreen_native->gbm.next_fb == NULL);
+      if (onscreen_native->gbm.next_fb != NULL)
+        {
+          CoglFrameInfo *frame_info;
+
+          frame_info = cogl_onscreen_peek_head_frame_info (onscreen);
+          frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
+          meta_onscreen_native_notify_frame_complete (onscreen);
+        }
+
       if (onscreen_native->secondary_gpu_state)
         g_set_object (&onscreen_native->gbm.next_fb, secondary_gpu_fb);
       else
-- 
GitLab

From a7bf66b5df4c1409141973ddb40c096d08ee1e79 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 5 Dec 2023 17:50:44 +0800
Subject: [PATCH 11/31] onscreen/native: Insert a 'posted' frame between 'next'
 and 'current'

This will allow us to keep track of up to two buffers that have been
swapped but not yet scanning out, for triple buffering.

This commit replaces mutter!1968.
---
 src/backends/native/meta-onscreen-native.c | 58 ++++++++++++----------
 1 file changed, 31 insertions(+), 27 deletions(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index eaa00d45a86..2617b160674 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -98,8 +98,10 @@ struct _MetaOnscreenNative
   struct {
     struct gbm_surface *surface;
     MetaDrmBuffer *current_fb;
+    MetaDrmBuffer *posted_fb;
     MetaDrmBuffer *next_fb;
     CoglScanout *current_scanout;
+    CoglScanout *posted_scanout;
     CoglScanout *next_scanout;
   } gbm;
 
@@ -146,39 +148,30 @@ init_secondary_gpu_state (MetaRendererNative  *renderer_native,
                           CoglOnscreen        *onscreen,
                           GError             **error);
 
-static void
-free_current_bo (CoglOnscreen *onscreen)
-{
-  MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
-
-  g_clear_object (&onscreen_native->gbm.current_fb);
-  g_clear_object (&onscreen_native->gbm.current_scanout);
-}
-
 static void
 meta_onscreen_native_swap_drm_fb (CoglOnscreen *onscreen)
 {
   MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
 
-  if (!onscreen_native->gbm.next_fb)
+  if (!onscreen_native->gbm.posted_fb)
     return;
 
-  free_current_bo (onscreen);
+  g_set_object (&onscreen_native->gbm.current_fb,
+                onscreen_native->gbm.posted_fb);
+  g_clear_object (&onscreen_native->gbm.posted_fb);
 
-  g_set_object (&onscreen_native->gbm.current_fb, onscreen_native->gbm.next_fb);
-  g_clear_object (&onscreen_native->gbm.next_fb);
   g_set_object (&onscreen_native->gbm.current_scanout,
-                onscreen_native->gbm.next_scanout);
-  g_clear_object (&onscreen_native->gbm.next_scanout);
+                onscreen_native->gbm.posted_scanout);
+  g_clear_object (&onscreen_native->gbm.posted_scanout);
 }
 
 static void
-meta_onscreen_native_clear_next_fb (CoglOnscreen *onscreen)
+meta_onscreen_native_clear_posted_fb (CoglOnscreen *onscreen)
 {
   MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
 
-  g_clear_object (&onscreen_native->gbm.next_fb);
-  g_clear_object (&onscreen_native->gbm.next_scanout);
+  g_clear_object (&onscreen_native->gbm.posted_fb);
+  g_clear_object (&onscreen_native->gbm.posted_scanout);
 }
 
 static void
@@ -359,7 +352,7 @@ page_flip_feedback_discarded (MetaKmsCrtc  *kms_crtc,
   frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
 
   meta_onscreen_native_notify_frame_complete (onscreen);
-  meta_onscreen_native_clear_next_fb (onscreen);
+  meta_onscreen_native_clear_posted_fb (onscreen);
 }
 
 static const MetaKmsPageFlipListenerVtable page_flip_listener_vtable = {
@@ -530,13 +523,21 @@ meta_onscreen_native_flip_crtc (CoglOnscreen           *onscreen,
   switch (renderer_gpu_data->mode)
     {
     case META_RENDERER_NATIVE_MODE_GBM:
-      buffer = onscreen_native->gbm.next_fb;
+      g_set_object (&onscreen_native->gbm.posted_fb,
+                    onscreen_native->gbm.next_fb);
+      g_clear_object (&onscreen_native->gbm.next_fb);
+
+      buffer = onscreen_native->gbm.posted_fb;
+
+      g_set_object (&onscreen_native->gbm.posted_scanout,
+                    onscreen_native->gbm.next_scanout);
+      g_clear_object (&onscreen_native->gbm.next_scanout);
 
-      if (onscreen_native->gbm.next_scanout)
+      if (onscreen_native->gbm.posted_scanout)
         {
-          cogl_scanout_get_src_rect (onscreen_native->gbm.next_scanout,
+          cogl_scanout_get_src_rect (onscreen_native->gbm.posted_scanout,
                                      &src_rect);
-          cogl_scanout_get_dst_rect (onscreen_native->gbm.next_scanout,
+          cogl_scanout_get_dst_rect (onscreen_native->gbm.posted_scanout,
                                      &dst_rect);
         }
       else
@@ -1267,7 +1268,7 @@ swap_buffer_result_feedback (const MetaKmsFeedback *kms_feedback,
   frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
 
   meta_onscreen_native_notify_frame_complete (onscreen);
-  meta_onscreen_native_clear_next_fb (onscreen);
+  meta_onscreen_native_clear_posted_fb (onscreen);
 }
 
 static const MetaKmsResultListenerVtable swap_buffer_result_listener_vtable = {
@@ -1632,7 +1633,7 @@ scanout_result_feedback (const MetaKmsFeedback *kms_feedback,
 
       g_warning ("Direct scanout page flip failed: %s", error->message);
 
-      cogl_scanout_notify_failed (onscreen_native->gbm.next_scanout,
+      cogl_scanout_notify_failed (onscreen_native->gbm.posted_scanout,
                                   onscreen);
       clutter_stage_view_add_redraw_clip (view, NULL);
       clutter_stage_view_schedule_update_now (view);
@@ -1642,7 +1643,7 @@ scanout_result_feedback (const MetaKmsFeedback *kms_feedback,
   frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
 
   meta_onscreen_native_notify_frame_complete (onscreen);
-  meta_onscreen_native_clear_next_fb (onscreen);
+  meta_onscreen_native_clear_posted_fb (onscreen);
 }
 
 static const MetaKmsResultListenerVtable scanout_result_listener_vtable = {
@@ -2882,8 +2883,11 @@ meta_onscreen_native_dispose (GObject *object)
     {
     case META_RENDERER_NATIVE_MODE_GBM:
       g_clear_object (&onscreen_native->gbm.next_fb);
+      g_clear_object (&onscreen_native->gbm.posted_fb);
+      g_clear_object (&onscreen_native->gbm.current_fb);
       g_clear_object (&onscreen_native->gbm.next_scanout);
-      free_current_bo (onscreen);
+      g_clear_object (&onscreen_native->gbm.posted_scanout);
+      g_clear_object (&onscreen_native->gbm.current_scanout);
       break;
     case META_RENDERER_NATIVE_MODE_SURFACELESS:
       g_assert_not_reached ();
-- 
GitLab

From ae8e1d0c626f6c2e6be615b3453b5085b0711a68 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 17 Sep 2021 17:59:28 +0800
Subject: [PATCH 12/31] onscreen/native: Defer posting if there's already a
 post in progress

And when the number of pending posts decreases we know it's safe to submit
a new one. Since KMS generally only supports one outstanding post right now,
"decreases" means equal to zero.
---
 src/backends/native/meta-onscreen-native.c | 192 ++++++++++++++++++---
 1 file changed, 164 insertions(+), 28 deletions(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 2617b160674..d57aad0b28f 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -100,9 +100,11 @@ struct _MetaOnscreenNative
     MetaDrmBuffer *current_fb;
     MetaDrmBuffer *posted_fb;
     MetaDrmBuffer *next_fb;
+    MetaDrmBuffer *stalled_fb;
     CoglScanout *current_scanout;
     CoglScanout *posted_scanout;
     CoglScanout *next_scanout;
+    CoglScanout *stalled_scanout;
   } gbm;
 
 #ifdef HAVE_EGL_DEVICE
@@ -128,6 +130,10 @@ struct _MetaOnscreenNative
   gulong color_space_changed_handler_id;
   gulong hdr_metadata_changed_handler_id;
 
+  gboolean needs_flush;
+
+  unsigned int swaps_pending;
+
   struct {
     int *rectangles;  /* 4 x n_rectangles */
     int n_rectangles;
@@ -141,7 +147,11 @@ G_DEFINE_TYPE (MetaOnscreenNative, meta_onscreen_native,
 static GQuark blit_source_quark = 0;
 
 static void
-post_latest_swap (CoglOnscreen *onscreen);
+try_post_latest_swap (CoglOnscreen *onscreen);
+
+static void
+post_finish_frame (MetaOnscreenNative *onscreen_native,
+                   MetaKmsUpdate      *kms_update);
 
 static gboolean
 init_secondary_gpu_state (MetaRendererNative  *renderer_native,
@@ -245,6 +255,7 @@ notify_view_crtc_presented (MetaRendererView *view,
 
   meta_onscreen_native_notify_frame_complete (onscreen);
   meta_onscreen_native_swap_drm_fb (onscreen);
+  try_post_latest_swap (onscreen);
 }
 
 static void
@@ -294,15 +305,13 @@ page_flip_feedback_ready (MetaKmsCrtc *kms_crtc,
   CoglFramebuffer *framebuffer =
     clutter_stage_view_get_onscreen (CLUTTER_STAGE_VIEW (view));
   CoglOnscreen *onscreen = COGL_ONSCREEN (framebuffer);
-  MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
   CoglFrameInfo *frame_info;
 
   frame_info = cogl_onscreen_peek_head_frame_info (onscreen);
   frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
 
-  g_warn_if_fail (!onscreen_native->gbm.next_fb);
-
   meta_onscreen_native_notify_frame_complete (onscreen);
+  try_post_latest_swap (onscreen);
 }
 
 static void
@@ -353,6 +362,7 @@ page_flip_feedback_discarded (MetaKmsCrtc  *kms_crtc,
 
   meta_onscreen_native_notify_frame_complete (onscreen);
   meta_onscreen_native_clear_posted_fb (onscreen);
+  try_post_latest_swap (onscreen);
 }
 
 static const MetaKmsPageFlipListenerVtable page_flip_listener_vtable = {
@@ -413,18 +423,41 @@ custom_egl_stream_page_flip (gpointer custom_page_flip_data,
 }
 #endif /* HAVE_EGL_DEVICE */
 
-void
-meta_onscreen_native_dummy_power_save_page_flip (CoglOnscreen *onscreen)
+static void
+drop_stalled_swap (CoglOnscreen *onscreen)
 {
   CoglFrameInfo *frame_info;
+  MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
 
-  meta_onscreen_native_swap_drm_fb (onscreen);
+  /* Remember we can't compare stalled_fb because it's not used by
+   * META_RENDERER_NATIVE_MODE_EGL_DEVICE. So we judge stalled to be whenever
+   * swaps_pending > 1.
+   */
+  if (onscreen_native->swaps_pending <= 1)
+    return;
+
+  onscreen_native->swaps_pending--;
+
+  g_clear_object (&onscreen_native->gbm.stalled_fb);
+  g_clear_object (&onscreen_native->gbm.stalled_scanout);
 
   frame_info = cogl_onscreen_peek_tail_frame_info (onscreen);
   frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
   meta_onscreen_native_notify_frame_complete (onscreen);
 }
 
+void
+meta_onscreen_native_dummy_power_save_page_flip (CoglOnscreen *onscreen)
+{
+  drop_stalled_swap (onscreen);
+
+  /* If the monitor just woke up and the shell is fully idle (has nothing
+   * more to swap) then we just woke to an indefinitely black screen. Let's
+   * fix that using the last swap (which is never classified as "stalled").
+   */
+  try_post_latest_swap (onscreen);
+}
+
 static void
 apply_transform (MetaCrtcKms            *crtc_kms,
                  MetaKmsPlaneAssignment *kms_plane_assignment,
@@ -1265,9 +1298,16 @@ swap_buffer_result_feedback (const MetaKmsFeedback *kms_feedback,
     g_warning ("Page flip failed: %s", error->message);
 
   frame_info = cogl_onscreen_peek_head_frame_info (onscreen);
-  frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
 
-  meta_onscreen_native_notify_frame_complete (onscreen);
+  /* After resuming from suspend, drop_stalled_swap might have done this
+   * already and emptied the frame_info queue.
+   */
+  if (frame_info)
+    {
+      frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
+      meta_onscreen_native_notify_frame_complete (onscreen);
+    }
+
   meta_onscreen_native_clear_posted_fb (onscreen);
 }
 
@@ -1394,14 +1434,15 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   switch (renderer_gpu_data->mode)
     {
     case META_RENDERER_NATIVE_MODE_GBM:
-      g_warn_if_fail (onscreen_native->gbm.next_fb == NULL);
       if (onscreen_native->gbm.next_fb != NULL)
         {
-          CoglFrameInfo *frame_info;
-
-          frame_info = cogl_onscreen_peek_head_frame_info (onscreen);
-          frame_info->flags |= COGL_FRAME_INFO_FLAG_SYMBOLIC;
-          meta_onscreen_native_notify_frame_complete (onscreen);
+          g_warn_if_fail (onscreen_native->gbm.stalled_fb == NULL);
+          drop_stalled_swap (onscreen);
+          g_assert (onscreen_native->gbm.stalled_fb == NULL);
+          onscreen_native->gbm.stalled_fb =
+            g_steal_pointer (&onscreen_native->gbm.next_fb);
+          onscreen_native->gbm.stalled_scanout =
+            g_steal_pointer (&onscreen_native->gbm.next_scanout);
         }
 
       if (onscreen_native->secondary_gpu_state)
@@ -1449,11 +1490,12 @@ meta_onscreen_native_swap_buffers_with_damage (CoglOnscreen  *onscreen,
   g_clear_pointer (&onscreen_native->next_post.frame, clutter_frame_unref);
   onscreen_native->next_post.frame = clutter_frame_ref (frame);
 
-  post_latest_swap (onscreen);
+  onscreen_native->swaps_pending++;
+  try_post_latest_swap (onscreen);
 }
 
 static void
-post_latest_swap (CoglOnscreen *onscreen)
+try_post_latest_swap (CoglOnscreen *onscreen)
 {
   CoglFramebuffer *framebuffer = COGL_FRAMEBUFFER (onscreen);
   CoglContext *cogl_context = cogl_framebuffer_get_context (framebuffer);
@@ -1472,15 +1514,41 @@ post_latest_swap (CoglOnscreen *onscreen)
   MetaKmsDevice *kms_device = meta_kms_crtc_get_device (kms_crtc);
   MetaKmsUpdate *kms_update;
   g_autoptr (MetaKmsFeedback) kms_feedback = NULL;
-  g_autoptr (ClutterFrame) frame =
-    g_steal_pointer (&onscreen_native->next_post.frame);
+  g_autoptr (ClutterFrame) frame = NULL;
   MetaFrameNative *frame_native;
 
+  if (onscreen_native->next_post.frame == NULL)
+    return;
+
   power_save_mode = meta_monitor_manager_get_power_save_mode (monitor_manager);
   if (power_save_mode == META_POWER_SAVE_ON)
     {
+      unsigned int frames_pending =
+        cogl_onscreen_count_pending_frames (onscreen);
+      unsigned int posts_pending;
+
+      g_assert (frames_pending >= onscreen_native->swaps_pending);
+      posts_pending = frames_pending - onscreen_native->swaps_pending;
+      if (posts_pending > 0)
+        return;  /* wait for the next frame notification and then try again */
+
+      frame = g_steal_pointer (&onscreen_native->next_post.frame);
       frame_native = meta_frame_native_from_frame (frame);
 
+      if (onscreen_native->swaps_pending == 0)
+        {
+          if (frame_native)
+            {
+              kms_update = meta_frame_native_steal_kms_update (frame_native);
+              if (kms_update)
+                post_finish_frame (onscreen_native, kms_update);
+            }
+          return;
+        }
+
+      drop_stalled_swap (onscreen);
+      onscreen_native->swaps_pending--;
+
       kms_update = meta_frame_native_ensure_kms_update (frame_native,
                                                         kms_device);
       meta_kms_update_add_result_listener (kms_update,
@@ -1695,6 +1763,18 @@ meta_onscreen_native_direct_scanout (CoglOnscreen   *onscreen,
       return FALSE;
     }
 
+  /* Our direct scanout frame counts as 1, so more than that means we would
+   * be jumping the queue (and post would fail).
+   */
+  if (cogl_onscreen_count_pending_frames (onscreen) > 1)
+    {
+      g_set_error_literal (error,
+                           COGL_SCANOUT_ERROR,
+                           COGL_SCANOUT_ERROR_INHIBITED,
+                           "Direct scanout is inhibited during triple buffering");
+      return FALSE;
+    }
+
   renderer_gpu_data = meta_renderer_native_get_gpu_data (renderer_native,
                                                          render_gpu);
 
@@ -1930,22 +2010,79 @@ meta_onscreen_native_finish_frame (CoglOnscreen *onscreen,
   MetaKmsDevice *kms_device = meta_kms_crtc_get_device (kms_crtc);
   MetaFrameNative *frame_native = meta_frame_native_from_frame (frame);
   MetaKmsUpdate *kms_update;
+  unsigned int frames_pending = cogl_onscreen_count_pending_frames (onscreen);
+  unsigned int swaps_pending = onscreen_native->swaps_pending;
+  unsigned int posts_pending = frames_pending - swaps_pending;
 
-  kms_update = meta_frame_native_steal_kms_update (frame_native);
-  if (!kms_update)
+  onscreen_native->needs_flush |= meta_kms_device_handle_flush (kms_device,
+                                                                kms_crtc);
+
+  if (!meta_frame_native_has_kms_update (frame_native))
     {
-      if (meta_kms_device_handle_flush (kms_device, kms_crtc))
-        {
-          kms_update = meta_kms_update_new (kms_device);
-          meta_kms_update_set_flushing (kms_update, kms_crtc);
-        }
-      else
+      if (!onscreen_native->needs_flush || posts_pending)
         {
           clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_IDLE);
           return;
         }
     }
 
+  if (posts_pending && !swaps_pending)
+    {
+      g_return_if_fail (meta_frame_native_has_kms_update (frame_native));
+      g_warn_if_fail (onscreen_native->next_post.frame == NULL);
+
+      g_clear_pointer (&onscreen_native->next_post.frame, clutter_frame_unref);
+      onscreen_native->next_post.frame = clutter_frame_ref (frame);
+      clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
+      return;
+    }
+
+  kms_update = meta_frame_native_steal_kms_update (frame_native);
+
+  if (posts_pending && swaps_pending)
+    {
+      MetaFrameNative *older_frame_native;
+      MetaKmsUpdate *older_kms_update;
+
+      g_return_if_fail (kms_update);
+      g_return_if_fail (onscreen_native->next_post.frame != NULL);
+
+      older_frame_native =
+        meta_frame_native_from_frame (onscreen_native->next_post.frame);
+      older_kms_update =
+        meta_frame_native_ensure_kms_update (older_frame_native, kms_device);
+      meta_kms_update_merge_from (older_kms_update, kms_update);
+      meta_kms_update_free (kms_update);
+      clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_IDLE);
+      return;
+    }
+
+  if (!kms_update)
+    {
+      kms_update = meta_kms_update_new (kms_device);
+      g_warn_if_fail (onscreen_native->needs_flush);
+    }
+
+  if (onscreen_native->needs_flush)
+    {
+      meta_kms_update_set_flushing (kms_update, kms_crtc);
+      onscreen_native->needs_flush = FALSE;
+    }
+
+  post_finish_frame (onscreen_native, kms_update);
+
+  clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
+}
+
+static void
+post_finish_frame (MetaOnscreenNative *onscreen_native,
+                   MetaKmsUpdate      *kms_update)
+{
+  MetaCrtc *crtc = onscreen_native->crtc;
+  MetaKmsCrtc *kms_crtc = meta_crtc_kms_get_kms_crtc (META_CRTC_KMS (crtc));
+  MetaKmsDevice *kms_device = meta_kms_crtc_get_device (kms_crtc);
+  g_autoptr (MetaKmsFeedback) kms_feedback = NULL;
+
   meta_kms_update_add_result_listener (kms_update,
                                        &finish_frame_result_listener_vtable,
                                        NULL,
@@ -1968,7 +2105,6 @@ meta_onscreen_native_finish_frame (CoglOnscreen *onscreen,
   meta_kms_update_set_flushing (kms_update, kms_crtc);
   meta_kms_device_post_update (kms_device, kms_update,
                                META_KMS_UPDATE_FLAG_NONE);
-  clutter_frame_set_result (frame, CLUTTER_FRAME_RESULT_PENDING_PRESENTED);
 }
 
 static gboolean
-- 
GitLab

From bce3e88e1300ef9644e80c912a39979aefc32e09 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 9 Dec 2022 14:22:31 +0800
Subject: [PATCH 13/31] onscreen/native: Increase secondary GPU dumb_fbs from 2
 to 3

So that they don't get overwritten prematurely during triple buffering
causing tearing.

https://launchpad.net/bugs/1999216
---
 src/backends/native/meta-onscreen-native.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index d57aad0b28f..a8e8dcfb7ab 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -76,7 +76,7 @@ typedef struct _MetaOnscreenNativeSecondaryGpuState
 
   struct {
     MetaDrmBufferDumb *current_dumb_fb;
-    MetaDrmBufferDumb *dumb_fbs[2];
+    MetaDrmBufferDumb *dumb_fbs[3];
   } cpu;
 
   gboolean noted_primary_gpu_copy_ok;
@@ -961,12 +961,17 @@ static MetaDrmBufferDumb *
 secondary_gpu_get_next_dumb_buffer (MetaOnscreenNativeSecondaryGpuState *secondary_gpu_state)
 {
   MetaDrmBufferDumb *current_dumb_fb;
+  const int n_dumb_fbs = G_N_ELEMENTS (secondary_gpu_state->cpu.dumb_fbs);
+  int i;
 
   current_dumb_fb = secondary_gpu_state->cpu.current_dumb_fb;
-  if (current_dumb_fb == secondary_gpu_state->cpu.dumb_fbs[0])
-    return secondary_gpu_state->cpu.dumb_fbs[1];
-  else
-    return secondary_gpu_state->cpu.dumb_fbs[0];
+  for (i = 0; i < n_dumb_fbs; i++)
+    {
+      if (current_dumb_fb == secondary_gpu_state->cpu.dumb_fbs[i])
+        return secondary_gpu_state->cpu.dumb_fbs[(i + 1) % n_dumb_fbs];
+    }
+
+  return secondary_gpu_state->cpu.dumb_fbs[0];
 }
 
 static MetaDrmBuffer *
-- 
GitLab

From 5d0e80d5eb7c2785fc0f0b830f2d647159974148 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 4 Nov 2021 16:09:26 +0800
Subject: [PATCH 14/31] onscreen/native: Add function
 meta_onscreen_native_discard_pending_swaps

---
 src/backends/native/meta-onscreen-native.c | 13 +++++++++++++
 src/backends/native/meta-onscreen-native.h |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index a8e8dcfb7ab..0c608237c96 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -2112,6 +2112,19 @@ post_finish_frame (MetaOnscreenNative *onscreen_native,
                                META_KMS_UPDATE_FLAG_NONE);
 }
 
+void
+meta_onscreen_native_discard_pending_swaps (CoglOnscreen *onscreen)
+{
+  MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
+
+  onscreen_native->swaps_pending = 0;
+
+  g_clear_object (&onscreen_native->gbm.stalled_fb);
+  g_clear_object (&onscreen_native->gbm.stalled_scanout);
+  g_clear_object (&onscreen_native->gbm.next_fb);
+  g_clear_object (&onscreen_native->gbm.next_scanout);
+}
+
 static gboolean
 should_surface_be_sharable (CoglOnscreen *onscreen)
 {
diff --git a/src/backends/native/meta-onscreen-native.h b/src/backends/native/meta-onscreen-native.h
index 0e1193325a9..e30357d19d1 100644
--- a/src/backends/native/meta-onscreen-native.h
+++ b/src/backends/native/meta-onscreen-native.h
@@ -48,6 +48,8 @@ void meta_onscreen_native_dummy_power_save_page_flip (CoglOnscreen *onscreen);
 gboolean meta_onscreen_native_is_buffer_scanout_compatible (CoglOnscreen *onscreen,
                                                             CoglScanout  *scanout);
 
+void meta_onscreen_native_discard_pending_swaps (CoglOnscreen *onscreen);
+
 void meta_onscreen_native_set_view (CoglOnscreen     *onscreen,
                                     MetaRendererView *view);
 
-- 
GitLab

From 89420b353c600b446439b5f0f2ccb68f3a3f46f8 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 11 May 2022 16:00:32 +0800
Subject: [PATCH 15/31] onscreen/native: Skip try_post_latest_swap if shutting
 down

Otherwise we could get:

meta_kms_prepare_shutdown ->
  flush_callbacks ->
  ... ->
  try_post_latest_swap ->
  post and queue more callbacks

So later in shutdown those callbacks would trigger an assertion failure
in meta_kms_impl_device_atomic_finalize:

g_hash_table_size (impl_device_atomic->page_flip_datas) == 0
---
 src/backends/native/meta-onscreen-native.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 0c608237c96..65e48f2ea35 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1510,6 +1510,8 @@ try_post_latest_swap (CoglOnscreen *onscreen)
   MetaRendererNative *renderer_native = renderer_gpu_data->renderer_native;
   MetaRenderer *renderer = META_RENDERER (renderer_native);
   MetaBackend *backend = meta_renderer_get_backend (renderer);
+  MetaBackendNative *backend_native = META_BACKEND_NATIVE (backend);
+  MetaKms *kms = meta_backend_native_get_kms (backend_native);
   MetaMonitorManager *monitor_manager =
     meta_backend_get_monitor_manager (backend);
   MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
@@ -1522,7 +1524,8 @@ try_post_latest_swap (CoglOnscreen *onscreen)
   g_autoptr (ClutterFrame) frame = NULL;
   MetaFrameNative *frame_native;
 
-  if (onscreen_native->next_post.frame == NULL)
+  if (onscreen_native->next_post.frame == NULL ||
+      meta_kms_is_shutting_down (kms))
     return;
 
   power_save_mode = meta_monitor_manager_get_power_save_mode (monitor_manager);
-- 
GitLab

From c8cef94592955afa7f07284489123e3d4255de90 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 4 Nov 2021 16:09:52 +0800
Subject: [PATCH 16/31] renderer/native: Discard pending swaps when rebuilding
 views

It's analogous to discard_pending_page_flips but represents swaps that
might become flips after the next frame notification callbacks, thanks
to triple buffering. Since the views are being rebuilt and their onscreens
are about to be destroyed, turning those swaps into more flips/posts would
just lead to unexpected behaviour (like trying to flip on a half-destroyed
inactive CRTC).
---
 src/backends/native/meta-renderer-native.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/backends/native/meta-renderer-native.c b/src/backends/native/meta-renderer-native.c
index 601fd674a49..3c22b4e86a7 100644
--- a/src/backends/native/meta-renderer-native.c
+++ b/src/backends/native/meta-renderer-native.c
@@ -1538,6 +1538,26 @@ detach_onscreens (MetaRenderer *renderer)
     }
 }
 
+static void
+discard_pending_swaps (MetaRenderer *renderer)
+{
+  GList *views = meta_renderer_get_views (renderer);;
+  GList *l;
+
+  for (l = views; l; l = l->next)
+    {
+      ClutterStageView *stage_view = l->data;
+      CoglFramebuffer *fb = clutter_stage_view_get_onscreen (stage_view);
+      CoglOnscreen *onscreen;
+
+      if (!COGL_IS_ONSCREEN (fb))
+        continue;
+
+      onscreen = COGL_ONSCREEN (fb);
+      meta_onscreen_native_discard_pending_swaps (onscreen);
+    }
+}
+
 static void
 meta_renderer_native_rebuild_views (MetaRenderer *renderer)
 {
@@ -1548,6 +1568,7 @@ meta_renderer_native_rebuild_views (MetaRenderer *renderer)
   MetaRendererClass *parent_renderer_class =
     META_RENDERER_CLASS (meta_renderer_native_parent_class);
 
+  discard_pending_swaps (renderer);
   meta_kms_discard_pending_page_flips (kms);
   g_hash_table_remove_all (renderer_native->mode_set_updates);
 
-- 
GitLab

From ba7e5942c6e8fcba136b4107d5bc201a151e3a10 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 7 Dec 2023 16:28:20 +0800
Subject: [PATCH 17/31] clutter/frame-clock: Reuse existing idle period
 detection

While it was correct for double buffering, the test was wrong for
triple buffering and would lead to accidentally staying in triple
buffering for too long.

Fixes: 8f27ebf87eee6057992a90560d4118ab7bdf138d
---
 clutter/clutter/clutter-frame-clock.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 30a319f6045..0c578a7af2a 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -496,6 +496,7 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
   int64_t min_render_time_allowed_us;
   int64_t max_render_time_allowed_us;
   int64_t next_presentation_time_us;
+  int64_t next_smooth_presentation_time_us;
   int64_t next_update_time_us;
 
   now_us = g_get_monotonic_time ();
@@ -540,7 +541,8 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
    *
    */
   last_presentation_time_us = frame_clock->last_presentation_time_us;
-  next_presentation_time_us = last_presentation_time_us + refresh_interval_us;
+  next_smooth_presentation_time_us = last_presentation_time_us + refresh_interval_us;
+  next_presentation_time_us = next_smooth_presentation_time_us;
 
   /*
    * However, the last presentation could have happened more than a frame ago.
@@ -607,7 +609,7 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
     }
 
   if (frame_clock->last_presentation_flags & CLUTTER_FRAME_INFO_FLAG_VSYNC &&
-      next_presentation_time_us != last_presentation_time_us + refresh_interval_us)
+      next_presentation_time_us != next_smooth_presentation_time_us)
     {
       /* There was an idle period since the last presentation, so there seems
        * be no constantly updating actor. In this case it's best to start
-- 
GitLab

From e78549083cc949a74a0a1610dbae8d76432c3cab Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 10 Aug 2021 17:46:49 +0800
Subject: [PATCH 18/31] clutter/frame-clock: Lower the threshold for disabling
 error diffusion

Error diffusion was introduced in 0555a5bbc15 for Nvidia where last
presentation time is always unknown (zero). Dispatch times would drift
apart always being a fraction of a frame late, and accumulated to cause
periodic frame skips. So error diffusion corrected that precisely and
avoided the skips.

That works great with double buffering but less great with triple
buffering. It's certainly still needed with triple buffering but
correcting for a lateness of many milliseconds isn't a good idea. That's
because a dispatch being that late is not due to main loop jitter but due
to Nvidia's swap buffers blocking when the queue is full. So scheduling
the next frame even earlier using last_dispatch_lateness_us would just
perpetuate the problem of swap buffers blocking for too long.

So now we lower the threshold of when error diffusion gets disabled. It's
still high enough to fix the original smoothness problem it was for, but
now low enough to detect Nvidia's occasionally blocking swaps and backs
off in that case.

Since the average duration of a blocking swap is half a frame interval
and we want to distinguish between that and sub-millisecond jitter, the
logical threshold is halfway again: refresh_interval_us/4.
---
 clutter/clutter/clutter-frame-clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 0c578a7af2a..d1a9f25c978 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -930,7 +930,7 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
                              frame_clock->refresh_interval_us;
 
   lateness_us = time_us - ideal_dispatch_time_us;
-  if (lateness_us < 0 || lateness_us >= frame_clock->refresh_interval_us)
+  if (lateness_us < 0 || lateness_us >= frame_clock->refresh_interval_us / 4)
     frame_clock->last_dispatch_lateness_us = 0;
   else
     frame_clock->last_dispatch_lateness_us = lateness_us;
-- 
GitLab

From 9d334a9242ef0a9e48edf77f620eefbdcda80683 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 24 Jul 2020 14:13:11 +0800
Subject: [PATCH 19/31] clutter/frame-clock: Merge states DISPATCHING and
 PENDING_PRESENTED

Chronologically they already overlap in time as presentation may
complete in the middle of the dispatch function, otherwise they are
contiguous in time. And most switch statements treated the two states
the same already so they're easy to merge into a single `DISPATCHED`
state.

Having fewer states now will make life easier when we add more states
later.
---
 clutter/clutter/clutter-frame-clock.c | 31 ++++++++++-----------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index d1a9f25c978..e00f5c8a346 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -70,8 +70,7 @@ typedef enum _ClutterFrameClockState
   CLUTTER_FRAME_CLOCK_STATE_IDLE,
   CLUTTER_FRAME_CLOCK_STATE_SCHEDULED,
   CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW,
-  CLUTTER_FRAME_CLOCK_STATE_DISPATCHING,
-  CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED,
+  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED,
 } ClutterFrameClockState;
 
 struct _ClutterFrameClock
@@ -418,8 +417,7 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       g_warn_if_reached ();
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       maybe_reschedule_update (frame_clock);
       break;
@@ -440,8 +438,7 @@ clutter_frame_clock_notify_ready (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       g_warn_if_reached ();
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       maybe_reschedule_update (frame_clock);
       break;
@@ -741,8 +738,7 @@ clutter_frame_clock_inhibit (ClutterFrameClock *frame_clock)
           frame_clock->pending_reschedule_now = TRUE;
           frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
           break;
-        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-        case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
           break;
         }
 
@@ -781,8 +777,7 @@ clutter_frame_clock_schedule_update_now (ClutterFrameClock *frame_clock)
       break;
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       return;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       frame_clock->pending_reschedule = TRUE;
       frame_clock->pending_reschedule_now = TRUE;
       return;
@@ -837,8 +832,7 @@ clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       return;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       frame_clock->pending_reschedule = TRUE;
       return;
     }
@@ -893,8 +887,7 @@ clutter_frame_clock_set_mode (ClutterFrameClock     *frame_clock,
       frame_clock->pending_reschedule_now = TRUE;
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       break;
     }
 
@@ -954,7 +947,7 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
   frame_clock->last_dispatch_time_us = time_us;
   g_source_set_ready_time (frame_clock->source, -1);
 
-  frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHING;
+  frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED;
 
   frame_count = frame_clock->frame_count++;
 
@@ -988,20 +981,20 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
   switch (frame_clock->state)
     {
     case CLUTTER_FRAME_CLOCK_STATE_INIT:
-    case CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED:
       g_warn_if_reached ();
       break;
     case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+      /* Presentation completed synchronously in the above listener */
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHING:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
       switch (result)
         {
         case CLUTTER_FRAME_RESULT_PENDING_PRESENTED:
-          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_PENDING_PRESENTED;
           break;
         case CLUTTER_FRAME_RESULT_IDLE:
+          /* The frame was aborted; nothing to paint/present */
           frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
           maybe_reschedule_update (frame_clock);
           break;
@@ -1218,8 +1211,6 @@ clutter_frame_clock_dispose (GObject *object)
 {
   ClutterFrameClock *frame_clock = CLUTTER_FRAME_CLOCK (object);
 
-  g_warn_if_fail (frame_clock->state != CLUTTER_FRAME_CLOCK_STATE_DISPATCHING);
-
   if (frame_clock->source)
     {
       g_signal_emit (frame_clock, signals[DESTROY], 0);
-- 
GitLab

From 7e2ab90c6d97a3d43c1ecb630c74dc4447524b3a Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Mon, 13 Dec 2021 17:03:44 +0800
Subject: [PATCH 20/31] clutter/frame-clock: Clamp render times to two frames,
 not one

Because the buffer queue may grow by an extra frame in triple buffering,
we need measurements exceeding one frame to indicate when and by how much
the scaling is necessary.
---
 clutter/clutter/clutter-frame-clock.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index e00f5c8a346..08524f5e35f 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -390,7 +390,7 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
         CLAMP (frame_clock->last_dispatch_lateness_us + dispatch_to_swap_us +
                MAX (swap_to_rendering_done_us, swap_to_flip_us),
                frame_clock->shortterm_max_update_duration_us,
-               frame_clock->refresh_interval_us);
+               2 * frame_clock->refresh_interval_us);
 
       maybe_update_longterm_max_duration_us (frame_clock, frame_info);
 
@@ -476,7 +476,7 @@ clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
     frame_clock->vblank_duration_us +
     clutter_max_render_time_constant_us;
 
-  max_render_time_us = CLAMP (max_render_time_us, 0, refresh_interval_us);
+  max_render_time_us = CLAMP (max_render_time_us, 0, 2 * refresh_interval_us);
 
   return max_render_time_us;
 }
-- 
GitLab

From 021091dfa3df4ef74f95d97edfb304a3fd371c02 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 10 Sep 2020 16:34:53 +0800
Subject: [PATCH 21/31] clutter/frame-clock: Add triple buffering support

---
 clutter/clutter/clutter-frame-clock.c | 191 ++++++++++++++++++++++----
 1 file changed, 163 insertions(+), 28 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 08524f5e35f..bd914ff03e6 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -70,7 +70,10 @@ typedef enum _ClutterFrameClockState
   CLUTTER_FRAME_CLOCK_STATE_IDLE,
   CLUTTER_FRAME_CLOCK_STATE_SCHEDULED,
   CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW,
-  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED,
+  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE,
+  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED,
+  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW,
+  CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO,
 } ClutterFrameClockState;
 
 struct _ClutterFrameClock
@@ -91,6 +94,7 @@ struct _ClutterFrameClock
   ClutterFrameClockMode mode;
 
   int64_t last_dispatch_time_us;
+  int64_t prev_last_dispatch_time_us;
   int64_t last_dispatch_lateness_us;
   int64_t last_presentation_time_us;
   int64_t next_update_time_us;
@@ -112,6 +116,7 @@ struct _ClutterFrameClock
   int64_t vblank_duration_us;
   /* Last KMS buffer submission time. */
   int64_t last_flip_time_us;
+  int64_t prev_last_flip_time_us;
 
   /* Last time we promoted short-term maximum to long-term one */
   int64_t longterm_promotion_us;
@@ -369,14 +374,35 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
       frame_info->has_valid_gpu_rendering_duration)
     {
       int64_t dispatch_to_swap_us, swap_to_rendering_done_us, swap_to_flip_us;
+      int64_t dispatch_time_us = 0, flip_time_us = 0;
+
+      switch (frame_clock->state)
+        {
+        case CLUTTER_FRAME_CLOCK_STATE_INIT:
+        case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+        case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
+        case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+          g_warn_if_reached ();
+          G_GNUC_FALLTHROUGH;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+          dispatch_time_us = frame_clock->last_dispatch_time_us;
+          flip_time_us = frame_clock->last_flip_time_us;
+          break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+          dispatch_time_us = frame_clock->prev_last_dispatch_time_us;
+          flip_time_us = frame_clock->prev_last_flip_time_us;
+          break;
+        }
 
       dispatch_to_swap_us =
         frame_info->cpu_time_before_buffer_swap_us -
-        frame_clock->last_dispatch_time_us;
+        dispatch_time_us;
       swap_to_rendering_done_us =
         frame_info->gpu_rendering_duration_ns / 1000;
       swap_to_flip_us =
-        frame_clock->last_flip_time_us -
+        flip_time_us -
         frame_info->cpu_time_before_buffer_swap_us;
 
       CLUTTER_NOTE (FRAME_TIMINGS,
@@ -417,10 +443,22 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       g_warn_if_reached ();
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       maybe_reschedule_update (frame_clock);
       break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
+      maybe_reschedule_update (frame_clock);
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW;
+      maybe_reschedule_update (frame_clock);
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+      maybe_reschedule_update (frame_clock);
+      break;
     }
 }
 
@@ -438,10 +476,22 @@ clutter_frame_clock_notify_ready (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
       g_warn_if_reached ();
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       maybe_reschedule_update (frame_clock);
       break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
+      maybe_reschedule_update (frame_clock);
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW;
+      maybe_reschedule_update (frame_clock);
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+      maybe_reschedule_update (frame_clock);
+      break;
     }
 }
 
@@ -456,7 +506,14 @@ clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
   if (!frame_clock->ever_got_measurements ||
       G_UNLIKELY (clutter_paint_debug_flags &
                   CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME))
-    return refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
+    {
+      int64_t ret = refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
+
+      if (frame_clock->state == CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE)
+        ret += refresh_interval_us;
+
+      return ret;
+    }
 
   /* Max render time shows how early the frame clock needs to be dispatched
    * to make it to the predicted next presentation time. It is an estimate of
@@ -493,7 +550,7 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
   int64_t min_render_time_allowed_us;
   int64_t max_render_time_allowed_us;
   int64_t next_presentation_time_us;
-  int64_t next_smooth_presentation_time_us;
+  int64_t next_smooth_presentation_time_us = 0;
   int64_t next_update_time_us;
 
   now_us = g_get_monotonic_time ();
@@ -538,7 +595,27 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
    *
    */
   last_presentation_time_us = frame_clock->last_presentation_time_us;
-  next_smooth_presentation_time_us = last_presentation_time_us + refresh_interval_us;
+  switch (frame_clock->state)
+    {
+    case CLUTTER_FRAME_CLOCK_STATE_INIT:
+    case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
+    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+      next_smooth_presentation_time_us = last_presentation_time_us +
+                                         refresh_interval_us;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+      next_smooth_presentation_time_us = last_presentation_time_us +
+                                         2 * refresh_interval_us;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+      next_smooth_presentation_time_us = last_presentation_time_us +
+                                         3 * refresh_interval_us;
+      break;
+    }
+
   next_presentation_time_us = next_smooth_presentation_time_us;
 
   /*
@@ -738,7 +815,17 @@ clutter_frame_clock_inhibit (ClutterFrameClock *frame_clock)
           frame_clock->pending_reschedule_now = TRUE;
           frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
           break;
-        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+          frame_clock->pending_reschedule = TRUE;
+          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+          break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+          frame_clock->pending_reschedule = TRUE;
+          frame_clock->pending_reschedule_now = TRUE;
+          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+          break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
           break;
         }
 
@@ -774,10 +861,17 @@ clutter_frame_clock_schedule_update_now (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_INIT:
     case CLUTTER_FRAME_CLOCK_STATE_IDLE:
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW;
       break;
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
       return;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+      frame_clock->state =
+        CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
       frame_clock->pending_reschedule = TRUE;
       frame_clock->pending_reschedule_now = TRUE;
       return;
@@ -806,7 +900,6 @@ clutter_frame_clock_schedule_update_now (ClutterFrameClock *frame_clock)
 
   frame_clock->next_update_time_us = next_update_time_us;
   g_source_set_ready_time (frame_clock->source, next_update_time_us);
-  frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW;
 }
 
 void
@@ -828,11 +921,17 @@ clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
       return;
     case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
       break;
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
       return;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
       frame_clock->pending_reschedule = TRUE;
       return;
     }
@@ -861,7 +960,6 @@ clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
 
   frame_clock->next_update_time_us = next_update_time_us;
   g_source_set_ready_time (frame_clock->source, next_update_time_us);
-  frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
 }
 
 void
@@ -877,6 +975,8 @@ clutter_frame_clock_set_mode (ClutterFrameClock     *frame_clock,
     {
     case CLUTTER_FRAME_CLOCK_STATE_INIT:
     case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
       break;
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
       frame_clock->pending_reschedule = TRUE;
@@ -887,7 +987,14 @@ clutter_frame_clock_set_mode (ClutterFrameClock     *frame_clock,
       frame_clock->pending_reschedule_now = TRUE;
       frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+      frame_clock->pending_reschedule = TRUE;
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+      frame_clock->pending_reschedule = TRUE;
+      frame_clock->pending_reschedule_now = TRUE;
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
       break;
     }
 
@@ -944,10 +1051,27 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
     }
 #endif
 
+  frame_clock->prev_last_dispatch_time_us = frame_clock->last_dispatch_time_us;
   frame_clock->last_dispatch_time_us = time_us;
   g_source_set_ready_time (frame_clock->source, -1);
 
-  frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED;
+  switch (frame_clock->state)
+    {
+    case CLUTTER_FRAME_CLOCK_STATE_INIT:
+    case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+      g_warn_if_reached ();
+      return;
+    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
+    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+      break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO;
+      break;
+    }
 
   frame_count = frame_clock->frame_count++;
 
@@ -978,26 +1102,36 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
   result = iface->frame (frame_clock, frame, frame_clock->listener.user_data);
   COGL_TRACE_END (ClutterFrameClockFrame);
 
-  switch (frame_clock->state)
+  switch (result)
     {
-    case CLUTTER_FRAME_CLOCK_STATE_INIT:
-      g_warn_if_reached ();
+    case CLUTTER_FRAME_RESULT_PENDING_PRESENTED:
       break;
-    case CLUTTER_FRAME_CLOCK_STATE_IDLE:
-      /* Presentation completed synchronously in the above listener */
-    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
-    case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
-      break;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED:
-      switch (result)
+    case CLUTTER_FRAME_RESULT_IDLE:
+      /* The frame was aborted; nothing to paint/present */
+      switch (frame_clock->state)
         {
-        case CLUTTER_FRAME_RESULT_PENDING_PRESENTED:
+        case CLUTTER_FRAME_CLOCK_STATE_INIT:
+        case CLUTTER_FRAME_CLOCK_STATE_IDLE:
+        case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED:
+        case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
+          g_warn_if_reached ();
           break;
-        case CLUTTER_FRAME_RESULT_IDLE:
-          /* The frame was aborted; nothing to paint/present */
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
           frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_IDLE;
           maybe_reschedule_update (frame_clock);
           break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
+          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED;
+          maybe_reschedule_update (frame_clock);
+          break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
+          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW;
+          maybe_reschedule_update (frame_clock);
+          break;
+        case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
+          frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE;
+          maybe_reschedule_update (frame_clock);
+          break;
         }
       break;
     }
@@ -1033,6 +1167,7 @@ void
 clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
                                       int64_t            flip_time_us)
 {
+  frame_clock->prev_last_flip_time_us = frame_clock->last_flip_time_us;
   frame_clock->last_flip_time_us = flip_time_us;
 }
 
-- 
GitLab

From 335ac3b14b213d9dcdffa84835090f3cae1b87d3 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Fri, 10 Dec 2021 16:28:04 +0800
Subject: [PATCH 22/31] clutter/frame-clock: Log N-buffers in
 CLUTTTER_DEBUG=frame-timings

---
 clutter/clutter/clutter-frame-clock.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index bd914ff03e6..b8072600453 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -281,6 +281,12 @@ void
 clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
                                       ClutterFrameInfo  *frame_info)
 {
+#ifdef CLUTTER_ENABLE_DEBUG
+  const char *debug_state =
+    frame_clock->state == CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO ?
+    "Triple buffering" : "Double buffering";
+#endif
+
   COGL_TRACE_BEGIN_SCOPED (ClutterFrameClockNotifyPresented,
                            "Clutter::FrameClock::presented()");
   COGL_TRACE_DESCRIBE (ClutterFrameClockNotifyPresented,
@@ -406,7 +412,8 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
         frame_info->cpu_time_before_buffer_swap_us;
 
       CLUTTER_NOTE (FRAME_TIMINGS,
-                    "update2dispatch %ld µs, dispatch2swap %ld µs, swap2render %ld µs, swap2flip %ld µs",
+                    "%s: update2dispatch %ld µs, dispatch2swap %ld µs, swap2render %ld µs, swap2flip %ld µs",
+                    debug_state,
                     frame_clock->last_dispatch_lateness_us,
                     dispatch_to_swap_us,
                     swap_to_rendering_done_us,
@@ -425,7 +432,8 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
     }
   else
     {
-      CLUTTER_NOTE (FRAME_TIMINGS, "update2dispatch %ld µs",
+      CLUTTER_NOTE (FRAME_TIMINGS, "%s: update2dispatch %ld µs",
+                    debug_state,
                     frame_clock->last_dispatch_lateness_us);
     }
 
-- 
GitLab

From 634f27ee6e8d50592fbef7e9298188532b007665 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 7 Sep 2021 19:08:15 +0800
Subject: [PATCH 23/31] clutter/frame: Add ClutterFrameHint to ClutterFrame

This will allow the backend to provide performance hints to the frame
clock in future.
---
 clutter/clutter/clutter-frame-clock.h   |  6 ++++++
 clutter/clutter/clutter-frame-private.h |  1 +
 clutter/clutter/clutter-frame.c         | 13 +++++++++++++
 clutter/clutter/clutter-frame.h         |  7 +++++++
 4 files changed, 27 insertions(+)

diff --git a/clutter/clutter/clutter-frame-clock.h b/clutter/clutter/clutter-frame-clock.h
index a7be5ef3167..5adf995098b 100644
--- a/clutter/clutter/clutter-frame-clock.h
+++ b/clutter/clutter/clutter-frame-clock.h
@@ -33,6 +33,12 @@ typedef enum _ClutterFrameResult
   CLUTTER_FRAME_RESULT_IDLE,
 } ClutterFrameResult;
 
+typedef enum _ClutterFrameHint
+{
+  CLUTTER_FRAME_HINT_NONE                     = 0,
+  CLUTTER_FRAME_HINT_DIRECT_SCANOUT_ATTEMPTED = 1 << 0,
+} ClutterFrameHint;
+
 #define CLUTTER_TYPE_FRAME_CLOCK (clutter_frame_clock_get_type ())
 CLUTTER_EXPORT
 G_DECLARE_FINAL_TYPE (ClutterFrameClock, clutter_frame_clock,
diff --git a/clutter/clutter/clutter-frame-private.h b/clutter/clutter/clutter-frame-private.h
index ef66b874edf..ce140560a89 100644
--- a/clutter/clutter/clutter-frame-private.h
+++ b/clutter/clutter/clutter-frame-private.h
@@ -36,6 +36,7 @@ struct _ClutterFrame
 
   gboolean has_result;
   ClutterFrameResult result;
+  ClutterFrameHint hints;
 };
 
 CLUTTER_EXPORT
diff --git a/clutter/clutter/clutter-frame.c b/clutter/clutter/clutter-frame.c
index 7436f9f182d..53c289b2c5a 100644
--- a/clutter/clutter/clutter-frame.c
+++ b/clutter/clutter/clutter-frame.c
@@ -115,3 +115,16 @@ clutter_frame_set_result (ClutterFrame       *frame,
   frame->result = result;
   frame->has_result = TRUE;
 }
+
+void
+clutter_frame_set_hint (ClutterFrame     *frame,
+                        ClutterFrameHint  hint)
+{
+  frame->hints |= hint;
+}
+
+ClutterFrameHint
+clutter_frame_get_hints (ClutterFrame *frame)
+{
+  return frame->hints;
+}
diff --git a/clutter/clutter/clutter-frame.h b/clutter/clutter/clutter-frame.h
index 34f0770bd7d..c7b3d02acb9 100644
--- a/clutter/clutter/clutter-frame.h
+++ b/clutter/clutter/clutter-frame.h
@@ -54,4 +54,11 @@ void clutter_frame_set_result (ClutterFrame       *frame,
 CLUTTER_EXPORT
 gboolean clutter_frame_has_result (ClutterFrame *frame);
 
+CLUTTER_EXPORT
+void clutter_frame_set_hint (ClutterFrame     *frame,
+                             ClutterFrameHint  hint);
+
+CLUTTER_EXPORT
+ClutterFrameHint clutter_frame_get_hints (ClutterFrame *frame);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC (ClutterFrame, clutter_frame_unref)
-- 
GitLab

From 9cd11cde088ecba34174f58517bad75fb8859b4a Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 7 Sep 2021 19:10:26 +0800
Subject: [PATCH 24/31] backends: Flag that the frame attempted direct scanout

We need this hint whether direct scanout succeeds or fails because it's
the mechanism by which we will tell the clock to enforce double buffering,
thus making direct scanout possible on future frames. Triple buffering
will be disabled until such time that direct scanout is not being attempted.
---
 src/backends/meta-stage-impl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/backends/meta-stage-impl.c b/src/backends/meta-stage-impl.c
index 7aa24439d73..727e1a5f30b 100644
--- a/src/backends/meta-stage-impl.c
+++ b/src/backends/meta-stage-impl.c
@@ -774,6 +774,8 @@ meta_stage_impl_redraw_view (ClutterStageWindow *stage_window,
     {
       g_autoptr (GError) error = NULL;
 
+      clutter_frame_set_hint (frame, CLUTTER_FRAME_HINT_DIRECT_SCANOUT_ATTEMPTED);
+
       if (meta_stage_impl_scanout_view (stage_impl,
                                         stage_view,
                                         scanout,
-- 
GitLab

From 8cb94abcb5b343a790fb001cd2a9d72af1d9142d Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 7 Sep 2021 19:15:18 +0800
Subject: [PATCH 25/31] clutter: Pass ClutterFrameHint(s) to the frame clock

---
 clutter/clutter/clutter-frame-clock.c |  8 ++++++--
 clutter/clutter/clutter-frame-clock.h |  5 +++--
 clutter/clutter/clutter-stage-view.c  | 11 +++++++++--
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index b8072600453..8f9b18019d3 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -118,6 +118,8 @@ struct _ClutterFrameClock
   int64_t last_flip_time_us;
   int64_t prev_last_flip_time_us;
 
+  ClutterFrameHint last_flip_hints;
+
   /* Last time we promoted short-term maximum to long-term one */
   int64_t longterm_promotion_us;
   /* Long-term maximum update duration */
@@ -1172,11 +1174,13 @@ frame_clock_source_dispatch (GSource     *source,
 }
 
 void
-clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
-                                      int64_t            flip_time_us)
+clutter_frame_clock_record_flip (ClutterFrameClock *frame_clock,
+                                 int64_t            flip_time_us,
+                                 ClutterFrameHint   hints)
 {
   frame_clock->prev_last_flip_time_us = frame_clock->last_flip_time_us;
   frame_clock->last_flip_time_us = flip_time_us;
+  frame_clock->last_flip_hints = hints;
 }
 
 GString *
diff --git a/clutter/clutter/clutter-frame-clock.h b/clutter/clutter/clutter-frame-clock.h
index 5adf995098b..bfc89bde091 100644
--- a/clutter/clutter/clutter-frame-clock.h
+++ b/clutter/clutter/clutter-frame-clock.h
@@ -108,7 +108,8 @@ void clutter_frame_clock_remove_timeline (ClutterFrameClock *frame_clock,
 CLUTTER_EXPORT
 float clutter_frame_clock_get_refresh_rate (ClutterFrameClock *frame_clock);
 
-void clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
-                                           int64_t            flip_time_us);
+void clutter_frame_clock_record_flip (ClutterFrameClock *frame_clock,
+                                      int64_t            flip_time_us,
+                                      ClutterFrameHint   hints);
 
 GString * clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock);
diff --git a/clutter/clutter/clutter-stage-view.c b/clutter/clutter/clutter-stage-view.c
index f5188e2acf3..d53e3778510 100644
--- a/clutter/clutter/clutter-stage-view.c
+++ b/clutter/clutter/clutter-stage-view.c
@@ -898,14 +898,21 @@ handle_frame_clock_frame (ClutterFrameClock *frame_clock,
 
       _clutter_stage_window_redraw_view (stage_window, view, frame);
 
-      clutter_frame_clock_record_flip_time (frame_clock,
-                                            g_get_monotonic_time ());
+      clutter_frame_clock_record_flip (frame_clock,
+                                       g_get_monotonic_time (),
+                                       clutter_frame_get_hints (frame));
 
       clutter_stage_emit_after_paint (stage, view, frame);
 
       if (_clutter_context_get_show_fps ())
         end_frame_timing_measurement (view);
     }
+  else
+    {
+      clutter_frame_clock_record_flip (frame_clock,
+                                       g_get_monotonic_time (),
+                                       clutter_frame_get_hints (frame));
+    }
 
   _clutter_stage_window_finish_frame (stage_window, view, frame);
 
-- 
GitLab

From 3ba49ac00a1069e44fc3d2c213c38d554d7b688c Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 7 Sep 2021 19:15:55 +0800
Subject: [PATCH 26/31] clutter/frame-clock: Conditionally disable triple
 buffering

1. When direct scanout is attempted

There's no compositing during direct scanout so the "render" time is zero.
Thus there is no need to implement triple buffering for direct scanouts.
Stick to double buffering and enjoy the lower latency.

2. If disabled by environment variable MUTTER_DEBUG_TRIPLE_BUFFERING

With possible values {never, auto, always} where auto is the default.

3. When VRR is in use

VRR calls `clutter_frame_clock_schedule_update_now` which would keep
the buffer queue full, which in turn prevented direct scanout mode.
Because OnscreenNative currently only supports direct scanout with
double buffering.

We now break that feedback loop by preventing triple buffering from
being scheduled when the frame clock mode becomes variable. Long term
this could also be solved by supporting triple buffering in direct
scanout mode. But whether or not that would be desirable given the
latency penalty remains to be seen.
---
 clutter/clutter/clutter-frame-clock.c | 70 ++++++++++++++++++++++++++-
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 8f9b18019d3..8fadf71d6e7 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -42,6 +42,15 @@ enum
 
 static guint signals[N_SIGNALS];
 
+typedef enum
+{
+  TRIPLE_BUFFERING_MODE_NEVER,
+  TRIPLE_BUFFERING_MODE_AUTO,
+  TRIPLE_BUFFERING_MODE_ALWAYS,
+} TripleBufferingMode;
+
+static TripleBufferingMode triple_buffering_mode = TRIPLE_BUFFERING_MODE_AUTO;
+
 #define SYNC_DELAY_FALLBACK_FRACTION 0.875
 
 #define MINIMUM_REFRESH_RATE 30.f
@@ -854,6 +863,25 @@ clutter_frame_clock_uninhibit (ClutterFrameClock *frame_clock)
     maybe_reschedule_update (frame_clock);
 }
 
+static gboolean
+want_triple_buffering (ClutterFrameClock *frame_clock)
+{
+  switch (triple_buffering_mode)
+    {
+    case TRIPLE_BUFFERING_MODE_NEVER:
+      return FALSE;
+    case TRIPLE_BUFFERING_MODE_AUTO:
+      return frame_clock->mode == CLUTTER_FRAME_CLOCK_MODE_FIXED &&
+             !(frame_clock->last_flip_hints &
+               CLUTTER_FRAME_HINT_DIRECT_SCANOUT_ATTEMPTED);
+    case TRIPLE_BUFFERING_MODE_ALWAYS:
+      return TRUE;
+    }
+
+  g_assert_not_reached ();
+  return FALSE;
+}
+
 void
 clutter_frame_clock_schedule_update_now (ClutterFrameClock *frame_clock)
 {
@@ -876,11 +904,18 @@ clutter_frame_clock_schedule_update_now (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW:
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
       return;
-    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED:
       frame_clock->state =
         CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW;
       break;
+    case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
+      if (want_triple_buffering (frame_clock))
+        {
+          frame_clock->state =
+            CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW;
+          break;
+        }
+      G_GNUC_FALLTHROUGH;
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
       frame_clock->pending_reschedule = TRUE;
       frame_clock->pending_reschedule_now = TRUE;
@@ -916,6 +951,11 @@ void
 clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
 {
   int64_t next_update_time_us = -1;
+  TripleBufferingMode current_mode = triple_buffering_mode;
+
+  if (current_mode == TRIPLE_BUFFERING_MODE_AUTO &&
+      !want_triple_buffering (frame_clock))
+    current_mode = TRIPLE_BUFFERING_MODE_NEVER;
 
   if (frame_clock->inhibit_count > 0)
     {
@@ -939,7 +979,23 @@ clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED_NOW:
       return;
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE:
-      frame_clock->state = CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED;
+      switch (current_mode)
+        {
+        case TRIPLE_BUFFERING_MODE_NEVER:
+          frame_clock->pending_reschedule = TRUE;
+          return;
+        case TRIPLE_BUFFERING_MODE_AUTO:
+          frame_clock->state =
+            CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED;
+          break;
+        case TRIPLE_BUFFERING_MODE_ALWAYS:
+          next_update_time_us = g_get_monotonic_time ();
+          frame_clock->next_presentation_time_us = 0;
+          frame_clock->is_next_presentation_time_valid = FALSE;
+          frame_clock->state =
+            CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE_AND_SCHEDULED;
+          goto got_update_time;
+        }
       break;
     case CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_TWO:
       frame_clock->pending_reschedule = TRUE;
@@ -966,6 +1022,7 @@ clutter_frame_clock_schedule_update (ClutterFrameClock *frame_clock)
       break;
     }
 
+got_update_time:
   g_warn_if_fail (next_update_time_us != -1);
 
   frame_clock->next_update_time_us = next_update_time_us;
@@ -1381,6 +1438,15 @@ static void
 clutter_frame_clock_class_init (ClutterFrameClockClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  const char *mode_str;
+
+  mode_str = g_getenv ("MUTTER_DEBUG_TRIPLE_BUFFERING");
+  if (!g_strcmp0 (mode_str, "never"))
+    triple_buffering_mode = TRIPLE_BUFFERING_MODE_NEVER;
+  else if (!g_strcmp0 (mode_str, "auto"))
+    triple_buffering_mode = TRIPLE_BUFFERING_MODE_AUTO;
+  else if (!g_strcmp0 (mode_str, "always"))
+    triple_buffering_mode = TRIPLE_BUFFERING_MODE_ALWAYS;
 
   object_class->dispose = clutter_frame_clock_dispose;
 
-- 
GitLab

From ab66bb59fbb8f1d596f26938bf8217b87c89fb41 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 30 Jun 2022 18:56:06 +0800
Subject: [PATCH 27/31] tests/native-kms-render: Fix failing client-scanout
 test

It was assuming an immediate transition from compositing (triple
buffering) to direct scanout (double buffering), whereas there is
a one frame delay in that transition as the buffer queue shrinks.
We don't lose any frames in the transition.
---
 src/tests/native-kms-render.c | 106 ++++++++++++++++++++++++++++------
 1 file changed, 87 insertions(+), 19 deletions(-)

diff --git a/src/tests/native-kms-render.c b/src/tests/native-kms-render.c
index f5ebc23fec7..2f870fdc331 100644
--- a/src/tests/native-kms-render.c
+++ b/src/tests/native-kms-render.c
@@ -39,6 +39,8 @@
 #include "tests/meta-wayland-test-driver.h"
 #include "tests/meta-wayland-test-utils.h"
 
+#define N_FRAMES_PER_TEST 30
+
 typedef struct
 {
   int number_of_frames_left;
@@ -46,12 +48,15 @@ typedef struct
 
   struct {
     int n_paints;
-    uint32_t fb_id;
+    int n_presentations;
+    int n_direct_scanouts;
+    GList *fb_ids;
   } scanout;
 
   gboolean wait_for_scanout;
 
   struct {
+    int scanouts_attempted;
     gboolean scanout_sabotaged;
     gboolean fallback_painted;
     guint repaint_guard_id;
@@ -101,7 +106,7 @@ meta_test_kms_render_basic (void)
   gulong handler_id;
 
   test = (KmsRenderingTest) {
-    .number_of_frames_left = 10,
+    .number_of_frames_left = N_FRAMES_PER_TEST,
     .loop = g_main_loop_new (NULL, FALSE),
   };
   handler_id = g_signal_connect (stage, "after-update",
@@ -123,7 +128,6 @@ on_scanout_before_update (ClutterStage     *stage,
                           KmsRenderingTest *test)
 {
   test->scanout.n_paints = 0;
-  test->scanout.fb_id = 0;
 }
 
 static void
@@ -135,6 +139,7 @@ on_scanout_before_paint (ClutterStage     *stage,
   CoglScanout *scanout;
   CoglScanoutBuffer *scanout_buffer;
   MetaDrmBuffer *buffer;
+  uint32_t fb_id;
 
   scanout = clutter_stage_view_peek_scanout (stage_view);
   if (!scanout)
@@ -143,8 +148,13 @@ on_scanout_before_paint (ClutterStage     *stage,
   scanout_buffer = cogl_scanout_get_buffer (scanout);
   g_assert_true (META_IS_DRM_BUFFER (scanout_buffer));
   buffer = META_DRM_BUFFER (scanout_buffer);
-  test->scanout.fb_id = meta_drm_buffer_get_fb_id (buffer);
-  g_assert_cmpuint (test->scanout.fb_id, >, 0);
+  fb_id = meta_drm_buffer_get_fb_id (buffer);
+  g_assert_cmpuint (fb_id, >, 0);
+  test->scanout.fb_ids = g_list_append (test->scanout.fb_ids,
+                                        GUINT_TO_POINTER (fb_id));
+
+  /* Triple buffering, but no higher */
+  g_assert_cmpuint (g_list_length (test->scanout.fb_ids), <=, 2);
 }
 
 static void
@@ -173,12 +183,12 @@ on_scanout_presented (ClutterStage     *stage,
   MetaDeviceFile *device_file;
   GError *error = NULL;
   drmModeCrtc *drm_crtc;
+  uint32_t first_fb_id_expected;
 
-  if (test->wait_for_scanout && test->scanout.n_paints > 0)
+  if (test->wait_for_scanout && test->scanout.fb_ids == NULL)
     return;
 
-  if (test->wait_for_scanout && test->scanout.fb_id == 0)
-    return;
+  test->scanout.n_presentations++;
 
   device_pool = meta_backend_native_get_device_pool (backend_native);
 
@@ -197,15 +207,41 @@ on_scanout_presented (ClutterStage     *stage,
   drm_crtc = drmModeGetCrtc (meta_device_file_get_fd (device_file),
                              meta_kms_crtc_get_id (kms_crtc));
   g_assert_nonnull (drm_crtc);
-  if (test->scanout.fb_id == 0)
-    g_assert_cmpuint (drm_crtc->buffer_id, !=, test->scanout.fb_id);
+
+  if (test->scanout.fb_ids)
+    {
+      test->scanout.n_direct_scanouts++;
+      first_fb_id_expected = GPOINTER_TO_UINT (test->scanout.fb_ids->data);
+      test->scanout.fb_ids = g_list_delete_link (test->scanout.fb_ids,
+                                                 test->scanout.fb_ids);
+    }
   else
-    g_assert_cmpuint (drm_crtc->buffer_id, ==, test->scanout.fb_id);
+    {
+      first_fb_id_expected = 0;
+    }
+
+  /* The buffer ID won't match on the first frame because switching from
+   * triple buffered compositing to double buffered direct scanout takes
+   * an extra frame to drain the queue. Thereafter we are in direct scanout
+   * mode and expect the buffer IDs to match.
+   */
+  if (test->scanout.n_presentations > 1)
+    {
+      if (first_fb_id_expected == 0)
+        g_assert_cmpuint (drm_crtc->buffer_id, !=, first_fb_id_expected);
+      else
+        g_assert_cmpuint (drm_crtc->buffer_id, ==, first_fb_id_expected);
+    }
+
   drmModeFreeCrtc (drm_crtc);
 
   meta_device_file_release (device_file);
 
-  g_main_loop_quit (test->loop);
+  test->number_of_frames_left--;
+  if (test->number_of_frames_left <= 0)
+    g_main_loop_quit (test->loop);
+  else
+    clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
 }
 
 typedef enum
@@ -244,7 +280,9 @@ meta_test_kms_render_client_scanout (void)
   g_assert_nonnull (wayland_test_client);
 
   test = (KmsRenderingTest) {
+    .number_of_frames_left = N_FRAMES_PER_TEST,
     .loop = g_main_loop_new (NULL, FALSE),
+    .scanout = {0},
     .wait_for_scanout = TRUE,
   };
 
@@ -270,7 +308,8 @@ meta_test_kms_render_client_scanout (void)
   clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
   g_main_loop_run (test.loop);
 
-  g_assert_cmpuint (test.scanout.fb_id, >, 0);
+  g_assert_cmpint (test.scanout.n_presentations, ==, N_FRAMES_PER_TEST);
+  g_assert_cmpint (test.scanout.n_direct_scanouts, ==, N_FRAMES_PER_TEST);
 
   g_debug ("Unmake fullscreen");
   window = meta_find_window_from_title (test_context, "dma-buf-scanout-test");
@@ -292,10 +331,15 @@ meta_test_kms_render_client_scanout (void)
   g_assert_cmpint (buffer_rect.y, ==, 10);
 
   test.wait_for_scanout = FALSE;
+  test.number_of_frames_left = N_FRAMES_PER_TEST;
+  test.scanout.n_presentations = 0;
+  test.scanout.n_direct_scanouts = 0;
+
   clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
   g_main_loop_run (test.loop);
 
-  g_assert_cmpuint (test.scanout.fb_id, ==, 0);
+  g_assert_cmpint (test.scanout.n_presentations, ==, N_FRAMES_PER_TEST);
+  g_assert_cmpint (test.scanout.n_direct_scanouts, ==, 0);
 
   g_debug ("Moving back to 0, 0");
   meta_window_move_frame (window, TRUE, 0, 0);
@@ -307,10 +351,15 @@ meta_test_kms_render_client_scanout (void)
   g_assert_cmpint (buffer_rect.y, ==, 0);
 
   test.wait_for_scanout = TRUE;
+  test.number_of_frames_left = N_FRAMES_PER_TEST;
+  test.scanout.n_presentations = 0;
+  test.scanout.n_direct_scanouts = 0;
+
   clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
   g_main_loop_run (test.loop);
 
-  g_assert_cmpuint (test.scanout.fb_id, >, 0);
+  g_assert_cmpint (test.scanout.n_presentations, ==, N_FRAMES_PER_TEST);
+  g_assert_cmpint (test.scanout.n_direct_scanouts, ==, N_FRAMES_PER_TEST);
 
   g_signal_handler_disconnect (stage, before_update_handler_id);
   g_signal_handler_disconnect (stage, before_paint_handler_id);
@@ -364,6 +413,15 @@ on_scanout_fallback_before_paint (ClutterStage     *stage,
   if (!scanout)
     return;
 
+  test->scanout_fallback.scanouts_attempted++;
+
+  /* The first scanout candidate frame will get composited due to triple
+   * buffering draining the queue to drop to double buffering. So don't
+   * sabotage that first frame.
+   */
+  if (test->scanout_fallback.scanouts_attempted < 2)
+    return;
+
   g_assert_false (test->scanout_fallback.scanout_sabotaged);
 
   if (is_atomic_mode_setting (kms_device))
@@ -401,6 +459,15 @@ on_scanout_fallback_paint_view (ClutterStage     *stage,
       g_clear_handle_id (&test->scanout_fallback.repaint_guard_id,
                          g_source_remove);
       test->scanout_fallback.fallback_painted = TRUE;
+      test->scanout_fallback.scanout_sabotaged = FALSE;
+    }
+  else if (test->scanout_fallback.scanouts_attempted == 1)
+    {
+      /* Now that we've seen the first scanout attempt that was inhibited by
+       * triple buffering, try a second frame. The second one should scanout
+       * and will be sabotaged.
+       */
+      clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
     }
 }
 
@@ -410,11 +477,11 @@ on_scanout_fallback_presented (ClutterStage     *stage,
                                ClutterFrameInfo *frame_info,
                                KmsRenderingTest *test)
 {
-  if (!test->scanout_fallback.scanout_sabotaged)
-    return;
+  if (test->scanout_fallback.fallback_painted)
+    g_main_loop_quit (test->loop);
 
-  g_assert_true (test->scanout_fallback.fallback_painted);
-  g_main_loop_quit (test->loop);
+  test->number_of_frames_left--;
+  g_assert_cmpint (test->number_of_frames_left, >, 0);
 }
 
 static void
@@ -443,6 +510,7 @@ meta_test_kms_render_client_scanout_fallback (void)
   g_assert_nonnull (wayland_test_client);
 
   test = (KmsRenderingTest) {
+    .number_of_frames_left = N_FRAMES_PER_TEST,
     .loop = g_main_loop_new (NULL, FALSE),
   };
 
-- 
GitLab

From f78347d513613bee4324fd541bdb2e7a1303435a Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Thu, 22 Jun 2023 15:19:53 +0800
Subject: [PATCH 28/31] onscreen/native: Avoid callbacks on "detached"
 onscreens

Detached onscreens have no valid view so avoid servicing callbacks on
them during/after sleep mode. As previously mentioned in 45bda2d969f.

Closes: https://launchpad.net/bugs/2020049
---
 src/backends/native/meta-onscreen-native.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 65e48f2ea35..b35021c4f06 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1525,6 +1525,7 @@ try_post_latest_swap (CoglOnscreen *onscreen)
   MetaFrameNative *frame_native;
 
   if (onscreen_native->next_post.frame == NULL ||
+      onscreen_native->view == NULL ||
       meta_kms_is_shutting_down (kms))
     return;
 
-- 
GitLab

From 04d15394fe4ab4dbc4ef962facb430e085697aa7 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 18 Jul 2023 16:08:25 +0800
Subject: [PATCH 29/31] clutter/frame-clock: Record measurements of zero for
 cursor-only updates

But only if we've ever got actual swap measurements
(COGL_FEATURE_ID_TIMESTAMP_QUERY). If it's supported then we now drop to
double buffering and get optimal latency on a burst of cursor-only
updates.

Closes: https://launchpad.net/bugs/2023363
---
 clutter/clutter/clutter-frame-clock.c | 28 +++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 8fadf71d6e7..1937dceee93 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -262,10 +262,6 @@ static void
 maybe_update_longterm_max_duration_us (ClutterFrameClock *frame_clock,
                                        ClutterFrameInfo  *frame_info)
 {
-  /* Do not update long-term max if there has been no measurement */
-  if (!frame_clock->shortterm_max_update_duration_us)
-    return;
-
   if ((frame_info->presentation_time - frame_clock->longterm_promotion_us) <
       G_USEC_PER_SEC)
     return;
@@ -387,8 +383,9 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
 
   frame_clock->got_measurements_last_frame = FALSE;
 
-  if (frame_info->cpu_time_before_buffer_swap_us != 0 &&
-      frame_info->has_valid_gpu_rendering_duration)
+  if ((frame_info->cpu_time_before_buffer_swap_us != 0 &&
+       frame_info->has_valid_gpu_rendering_duration) ||
+      frame_clock->ever_got_measurements)
     {
       int64_t dispatch_to_swap_us, swap_to_rendering_done_us, swap_to_flip_us;
       int64_t dispatch_time_us = 0, flip_time_us = 0;
@@ -413,14 +410,21 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
           break;
         }
 
-      dispatch_to_swap_us =
-        frame_info->cpu_time_before_buffer_swap_us -
-        dispatch_time_us;
+      if (frame_info->cpu_time_before_buffer_swap_us == 0)
+        {
+          /* Cursor-only updates with no "swap" or "flip" */
+          dispatch_to_swap_us = 0;
+          swap_to_flip_us = 0;
+        }
+      else
+        {
+          dispatch_to_swap_us = frame_info->cpu_time_before_buffer_swap_us -
+                                dispatch_time_us;
+          swap_to_flip_us = flip_time_us -
+                            frame_info->cpu_time_before_buffer_swap_us;
+        }
       swap_to_rendering_done_us =
         frame_info->gpu_rendering_duration_ns / 1000;
-      swap_to_flip_us =
-        flip_time_us -
-        frame_info->cpu_time_before_buffer_swap_us;
 
       CLUTTER_NOTE (FRAME_TIMINGS,
                     "%s: update2dispatch %ld µs, dispatch2swap %ld µs, swap2render %ld µs, swap2flip %ld µs",
-- 
GitLab

From f37655b3193701643f68fd1ce77e283da4e4f489 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 26 Jul 2023 17:27:10 +0800
Subject: [PATCH 30/31] backends/native: Make await_flush later and inlined

"Later" as in after GL is finished rendering so as to not block the deadline
timer from updating the cursor smoothly during long GL renders. Indeed this
could make a primary plane frame late in some cases but that's only when
going from idle to active, so there is no previous frame to observe stutter
within the primary plane. It does however fix observable stutter in the
cursor plane by not dropping/stalling an otherwise good cursor update in a
continuous stream of cursor updates.

"Inlined" as in we don't need most of `meta_kms_device_await_flush`. The
important part is that it calls `disarm_crtc_frame_deadline_timer` to avoid
attempting two posts at once. So that's all that is kept.

This also fixes a deadlock in triple buffering. By not cancelling the
cursor update during a GL render we're also not cancelling a primary plane
update that might have already been piggybacked onto it by `queue_update`.

Cherry picked from !3149
---
 src/backends/native/meta-kms-impl-device.c | 4 +++-
 src/backends/native/meta-onscreen-native.c | 4 ----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/backends/native/meta-kms-impl-device.c b/src/backends/native/meta-kms-impl-device.c
index 1bff6be33c6..a2cfadb14a4 100644
--- a/src/backends/native/meta-kms-impl-device.c
+++ b/src/backends/native/meta-kms-impl-device.c
@@ -1609,9 +1609,11 @@ meta_kms_impl_device_handle_update (MetaKmsImplDevice *impl_device,
       meta_kms_update_merge_from (crtc_frame->pending_update, update);
       meta_kms_update_free (update);
       update = g_steal_pointer (&crtc_frame->pending_update);
-      disarm_crtc_frame_deadline_timer (crtc_frame);
     }
 
+  if (crtc_frame->deadline.armed)
+    disarm_crtc_frame_deadline_timer (crtc_frame);
+
   meta_kms_device_handle_flush (priv->device, latch_crtc);
 
   feedback = do_process (impl_device, latch_crtc, update, flags);
diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index b35021c4f06..9836663d0c7 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -1899,11 +1899,7 @@ meta_onscreen_native_before_redraw (CoglOnscreen *onscreen,
                                     ClutterFrame *frame)
 {
   MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (onscreen);
-  MetaCrtcKms *crtc_kms = META_CRTC_KMS (onscreen_native->crtc);
-  MetaKmsCrtc *kms_crtc = meta_crtc_kms_get_kms_crtc (crtc_kms);
 
-  meta_kms_device_await_flush (meta_kms_crtc_get_device (kms_crtc),
-                               kms_crtc);
   maybe_update_frame_sync (onscreen_native, frame);
 }
 
-- 
GitLab

From bde7dc4e831da4cb7d0deca20d037587b5adc5f6 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Wed, 17 Jan 2024 17:21:03 +0800
Subject: [PATCH 31/31] clutter/frame-clock: Optimize latency for platforms
 missing TIMESTAMP_QUERY

Previously if we had no measurements then `compute_max_render_time_us`
would pessimise its answer to ensure triple buffering could be reached:
```
if (frame_clock->state == CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE)
  ret += refresh_interval_us;
```
But that also meant entering triple buffering even when not required.

Now we make `compute_max_render_time_us` more honest and return failure
if the answer isn't known (or is disabled). This in turn allows us to
optimize `calculate_next_update_time_us` for this special case, ensuring
triple buffering can be used, but isn't blindly always used.

This makes a visible difference to the latency when dragging windows in
Xorg, but will also help Wayland sessions on platforms lacking
TIMESTAMP_QUERY such as Raspberry Pi.
---
 clutter/clutter/clutter-frame-clock.c | 69 +++++++++++++++++----------
 1 file changed, 45 insertions(+), 24 deletions(-)

diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index 1937dceee93..75e33088c16 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -518,25 +518,18 @@ clutter_frame_clock_notify_ready (ClutterFrameClock *frame_clock)
     }
 }
 
-static int64_t
-clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
+static gboolean
+clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock,
+                                                int64_t           *max_render_time_us)
 {
   int64_t refresh_interval_us;
-  int64_t max_render_time_us;
 
   refresh_interval_us = frame_clock->refresh_interval_us;
 
   if (!frame_clock->ever_got_measurements ||
       G_UNLIKELY (clutter_paint_debug_flags &
                   CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME))
-    {
-      int64_t ret = refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
-
-      if (frame_clock->state == CLUTTER_FRAME_CLOCK_STATE_DISPATCHED_ONE)
-        ret += refresh_interval_us;
-
-      return ret;
-    }
+    return FALSE;
 
   /* Max render time shows how early the frame clock needs to be dispatched
    * to make it to the predicted next presentation time. It is an estimate of
@@ -550,15 +543,15 @@ clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
    * - The duration of vertical blank.
    * - A constant to account for variations in the above estimates.
    */
-  max_render_time_us =
+  *max_render_time_us =
     MAX (frame_clock->longterm_max_update_duration_us,
          frame_clock->shortterm_max_update_duration_us) +
     frame_clock->vblank_duration_us +
     clutter_max_render_time_constant_us;
 
-  max_render_time_us = CLAMP (max_render_time_us, 0, 2 * refresh_interval_us);
+  *max_render_time_us = CLAMP (*max_render_time_us, 0, 2 * refresh_interval_us);
 
-  return max_render_time_us;
+  return TRUE;
 }
 
 static void
@@ -575,6 +568,7 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
   int64_t next_presentation_time_us;
   int64_t next_smooth_presentation_time_us = 0;
   int64_t next_update_time_us;
+  gboolean max_render_time_is_known;
 
   now_us = g_get_monotonic_time ();
 
@@ -594,10 +588,13 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
     }
 
   min_render_time_allowed_us = refresh_interval_us / 2;
-  max_render_time_allowed_us =
-    clutter_frame_clock_compute_max_render_time_us (frame_clock);
 
-  if (min_render_time_allowed_us > max_render_time_allowed_us)
+  max_render_time_is_known =
+    clutter_frame_clock_compute_max_render_time_us (frame_clock,
+                                                    &max_render_time_allowed_us);
+
+  if (max_render_time_is_known &&
+      min_render_time_allowed_us > max_render_time_allowed_us)
     min_render_time_allowed_us = max_render_time_allowed_us;
 
   /*
@@ -718,6 +715,24 @@ calculate_next_update_time_us (ClutterFrameClock *frame_clock,
     }
   else
     {
+      /* If the max render time isn't known then using the current value of
+       * next_presentation_time_us is suboptimal. Targeting always one frame
+       * prior to that we'd lose the ability to scale up to triple buffering
+       * on late presentation. But targeting two frames prior we would be
+       * always triple buffering even when not required.
+       *   So the algorithm for deciding when to scale up to triple buffering
+       * in the absence of render time measurements is to simply target full
+       * frame rate. If we're keeping up then we'll stay double buffering. If
+       * we're not keeping up then this will switch us to triple buffering.
+       */
+      if (!max_render_time_is_known)
+        {
+          max_render_time_allowed_us =
+            refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
+          next_presentation_time_us =
+            last_presentation_time_us + refresh_interval_us;
+        }
+
       while (next_presentation_time_us - min_render_time_allowed_us < now_us)
         next_presentation_time_us += refresh_interval_us;
 
@@ -749,7 +764,9 @@ calculate_next_variable_update_time_us (ClutterFrameClock *frame_clock,
 
   refresh_interval_us = frame_clock->refresh_interval_us;
 
-  if (frame_clock->last_presentation_time_us == 0)
+  if (frame_clock->last_presentation_time_us == 0 ||
+      !clutter_frame_clock_compute_max_render_time_us (frame_clock,
+                                                       &max_render_time_allowed_us))
     {
       *out_next_update_time_us =
         frame_clock->last_dispatch_time_us ?
@@ -762,9 +779,6 @@ calculate_next_variable_update_time_us (ClutterFrameClock *frame_clock,
       return;
     }
 
-  max_render_time_allowed_us =
-    clutter_frame_clock_compute_max_render_time_us (frame_clock);
-
   last_presentation_time_us = frame_clock->last_presentation_time_us;
   next_presentation_time_us = last_presentation_time_us + refresh_interval_us;
 
@@ -1247,12 +1261,19 @@ clutter_frame_clock_record_flip (ClutterFrameClock *frame_clock,
 GString *
 clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock)
 {
+  int64_t max_render_time_us;
   int64_t max_update_duration_us;
   GString *string;
 
-  string = g_string_new (NULL);
-  g_string_append_printf (string, "Max render time: %ld µs",
-                          clutter_frame_clock_compute_max_render_time_us (frame_clock));
+  string = g_string_new ("Max render time: ");
+  if (!clutter_frame_clock_compute_max_render_time_us (frame_clock,
+                                                       &max_render_time_us))
+    {
+      g_string_append (string, "unknown");
+      return string;
+    }
+
+  g_string_append_printf (string, "%ld µs", max_render_time_us);
 
   if (frame_clock->got_measurements_last_frame)
     g_string_append_printf (string, " =");
-- 
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File _service:download_url:1441.patch of Package mutter (Revision 11a78eae7a78b4269c2a4fff2b4d81be)

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