On Wed, Jan 13, 2021 at 11:52 AM Veera Sundaram Sankaran <veeras@xxxxxxxxxxxxxx> wrote: > > The explicit out-fences in crtc are signaled as part of vblank event, > indicating all framebuffers present on the Atomic Commit request are > scanned out on the screen. Though the fence signal and the vblank event > notification happens at the same time, triggered by the same hardware > vsync event, the timestamp set in both are different. With drivers > supporting precise vblank timestamp the difference between the two > timestamps would be even higher. This might have an impact on use-mode > frameworks using these fence timestamps for purposes other than simple > buffer usage. For instance, the Android framework [1] uses the > retire-fences as an alternative to vblank when frame-updates are in > progress. Set the fence timestamp during send vblank event using a new > drm_send_event_timestamp_locked variant to avoid discrepancies. > > [1] https://android.googlesource.com/platform/frameworks/native/+/master/ > services/surfaceflinger/Scheduler/Scheduler.cpp#397 > > Changes in v2: > - Use drm_send_event_timestamp_locked to update fence timestamp > - add more information to commit text > > Changes in v3: > - use same backend helper function for variants of drm_send_event to > avoid code duplications > > Signed-off-by: Veera Sundaram Sankaran <veeras@xxxxxxxxxxxxxx> Looks good. I appreciate you addressing my earlier comments and sending this out again! Reviewed-by: John Stultz <john.stultz@xxxxxxxxxx> thanks -john
