[Intel-gfx] Video tearing on Sandybridge

Daniel Vetter daniel at ffwll.ch
Mon Apr 2 13:06:39 CEST 2012

On Mon, Apr 2, 2012 at 12:40, Oliver Seitz <info at vtnd.de> wrote:
>> The only workaround is [...]  to only use fullscreen DRI video
>> applications
>> (OpenGL or libva decoders) that use SwapBuffers.
> Yes, works perfectly while only one screen is connected. That means, this
> definition of "fullscreen" is "the whole framebuffer", and not "the content
> of one display"? This would in some way explain why tearing can not be
> reliably prevented while more than one screen is active.

Well, currently X has one framebuffer spanning all xrandr screens.
Which means we can't pageflip just one (it would show garbage on the
other screen). The fix would be to use per-crtc framebuffers for X,
which requires a decent rewrite of many things in X.

Yet again something else that Wayland gets right from the start ;-)
Daniel Vetter
daniel.vetter at ffwll.ch - +41 (0) 79 364 57 48 - http://blog.ffwll.ch

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