On Wed, Feb 13, 2019 at 10:56 AM Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > Quoting Daniel Vetter (2019-02-13 09:50:55) > > On Tue, Feb 12, 2019 at 10:32:31PM +0100, Mario Kleiner wrote: > > > I think all kms drivers try to call drm_crtc_handle_vblank() at start > > > of vblank to give Mesa the most time for frontbuffer rendering for > > > classic X. But vblank events are also used for scheduling bufferswaps > > > or other stuff for redirected windowed rendering, or via api's like > > > OML_sync_controls glXWaitForMscOML, so there might be other things > > > affected by a more delayed vblank handling. > > > > The frontbuffer rendering is very much X driver specific, and I think > > -amdgpu/radeon is the only one that requires this. No i915 driver ever > > used the vblank interrupt to schedule frontbuffer blits, we use some > > CS-side stalls. > > Fwiw, the Present midlayer does use vblank scheduling for inplace copy > updates. Not that I wish to encourage anyone to use frontbuffer > rendering. > -Chris Yes, that's what i meant. Under DRI2 at least AMD, Intel and nouveau have throttling based on CS stalls to avoid tearing and do throttling. DRI3/Present last time i checked just waited for a vblank event and then triggered the blit - something that causes tearing even when triggered at start of vblank. -mario _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
