onscreen/native: Mark GPU rendering duration as valid if supported

Since commit e30eb78891 `ClutterFrameClock` assumes that a valid CPU time
implies timestamp query support, which is also checked in
`cogl_onscreen_egl_swap_buffers_with_damage()`.

Unconditionally setting the CPU time on direct scanout meant that the
compositing path would be stuck on the last (direct scanout optimized)
result on GL implementations without timestamp query support since.

be0aa2976e (clutter/frame-clock: Avoid rapidly toggling dynamic max render time)

Fix that by explicitly marking the gpu rendering duration as valid when
querying the GPU timestamps is supported and check for it ClutterFrameClock.

Fixes: 56580ea7c9 ("backends/native: Assume zero rendering time for direct scanout buffers")
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3655>

clutter/clutter/clutter-frame-clock.c

@@ -361,7 +361,8 @@ 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)
+  if (frame_info->cpu_time_before_buffer_swap_us != 0 &&
+      frame_info->has_valid_gpu_rendering_duration)
     {
       int64_t dispatch_to_swap_us, swap_to_rendering_done_us, swap_to_flip_us;
 

clutter/clutter/clutter-stage.h

@@ -127,6 +127,7 @@ struct _ClutterFrameInfo
 
   unsigned int sequence;
 
+  gboolean has_valid_gpu_rendering_duration;
   int64_t gpu_rendering_duration_ns;
   int64_t cpu_time_before_buffer_swap_us;
 };

cogl/cogl/cogl-frame-info-private.h

@@ -74,6 +74,7 @@ struct _CoglFrameInfo
   unsigned int sequence;
 
   CoglTimestampQuery *timestamp_query;
+  gboolean has_valid_gpu_rendering_duration;
   int64_t gpu_time_before_buffer_swap_ns;
   int64_t cpu_time_before_buffer_swap_us;
 

cogl/cogl/cogl-frame-info.c

@@ -132,6 +132,12 @@ cogl_frame_info_get_sequence (CoglFrameInfo *info)
   return info->sequence;
 }
 
+gboolean
+cogl_frame_info_has_valid_gpu_rendering_duration (CoglFrameInfo *info)
+{
+  return info->has_valid_gpu_rendering_duration;
+}
+
 int64_t
 cogl_frame_info_get_rendering_duration_ns (CoglFrameInfo *info)
 {

cogl/cogl/cogl-frame-info.h

@@ -127,6 +127,9 @@ gboolean cogl_frame_info_is_vsync (CoglFrameInfo *info);
 COGL_EXPORT
 unsigned int cogl_frame_info_get_sequence (CoglFrameInfo *info);
 
+COGL_EXPORT
+gboolean cogl_frame_info_has_valid_gpu_rendering_duration (CoglFrameInfo *info);
+
 COGL_EXPORT
 int64_t cogl_frame_info_get_rendering_duration_ns (CoglFrameInfo *info);
 

cogl/cogl/winsys/cogl-onscreen-egl.c

@@ -318,6 +318,8 @@ cogl_onscreen_egl_swap_buffers_with_damage (CoglOnscreen  *onscreen,
       /* Set up a timestamp query for when all rendering will be finished. */
       info->timestamp_query =
         cogl_framebuffer_create_timestamp_query (COGL_FRAMEBUFFER (onscreen));
+
+      info->has_valid_gpu_rendering_duration = TRUE;
     }
 
   if (n_rectangles && priv->pf_eglSwapBuffersWithDamage)

src/backends/meta-stage-view.c

@@ -77,6 +77,8 @@ frame_cb (CoglOnscreen  *onscreen,
           cogl_frame_info_get_presentation_time_us (frame_info),
         .flags = flags,
         .sequence = cogl_frame_info_get_sequence (frame_info),
+        .has_valid_gpu_rendering_duration =
+          cogl_frame_info_has_valid_gpu_rendering_duration (frame_info),
         .gpu_rendering_duration_ns =
           cogl_frame_info_get_rendering_duration_ns (frame_info),
         .cpu_time_before_buffer_swap_us =

src/backends/native/meta-onscreen-native.c

@@ -1631,6 +1631,9 @@ meta_onscreen_native_direct_scanout (CoglOnscreen   *onscreen,
 
   frame_info->cpu_time_before_buffer_swap_us = g_get_monotonic_time ();
 
+  if (cogl_has_feature (cogl_context, COGL_FEATURE_ID_TIMESTAMP_QUERY))
+    frame_info->has_valid_gpu_rendering_duration = TRUE;
+
   kms_crtc = meta_crtc_kms_get_kms_crtc (META_CRTC_KMS (onscreen_native->crtc));
   kms_device = meta_kms_crtc_get_device (kms_crtc);
   kms_update = meta_frame_native_ensure_kms_update (frame_native, kms_device);