[Intel-gfx] vsync + vaapi question

Chris Wilson chris at chris-wilson.co.uk
Wed Dec 23 04:01:44 PST 2015

On Tue, Dec 22, 2015 at 11:25:53PM +0100, Lukas Hejtmanek wrote:
> On Tue, Dec 22, 2015 at 08:54:08PM +0000, Chris Wilson wrote:
> > Not really. The Primary output will be used as the vsync so long as a
> > single pixel of the Window is upon it. Fundamentally, we need to use the
> > output that the Window is on in order to driver the vblank update.
> Which window? Any window or the va-api window? In the latter case, it would be
> quite ok to setup left-of instead of clone and move mplayer window solely to
> the external monitor. Do I understand it correctly?

The clipped extents of the va-api Window is used to determine which CRTC
to use as the vblank source. Hmm, the Primary Output is used as the
preference (i.e. if any part of that Window is on the Primary, it is
used as the CRTC - the idea being that Primary is important and this
should share the vblank source for more Windows and prevent arbitrary
jumps between vblank sources as the Window moves).

Chris Wilson, Intel Open Source Technology Centre

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