Eric Anholt eric at anholt.net
Tue Apr 21 14:01:15 PDT 2009

On Tue, 2009-04-21 at 18:26 +0200, Olaf Ruppert wrote:
> On Tue, Apr 21, 2009 at 3:56 PM, Joakim Plate <elupus at ecce.se> wrote:
> > Just make sure you glFinish() before you wait for the vsync. Otherwise the call
> > to swap buffers take too long.
> >
> > I've seen this with SwapInterval extensions too.
> I tried all permutations of glFinish, drm-vsync and glXSwapBuffers.  I enabled
> vblank_interrupt in i830_dri.c  I compiled the drm_intel kernel, installed
> xorg-video-intel, mesa, etc. packages from debian unstable. No luck.
> I think I look at wrong problem. Maybe the probed modes are wrong.  I will
> check that tomorow.
> I'm frustrated.  All these boards are useless for me when there is no
> way to remove the tearing.  And it seems like I am the only one with
> this problem.

OK.  If you're using GLX_SGI_video_sync and it's failing, there are two
likely causes:
- You're using DRI2 and we haven't done vblank-synced swapping for DRI2
yet.  We were trying to come up with a decent way to support it, and we
now think we have.  Please hold on for a couple weeks.
- You're using DRI1 and it's syncing to the wrong CRTC when you have two
CRTCs enabled.

You may want to play with glsync (a trivial demo app in
mesa/progs/xdemos) on an idle machine to make sure it's ever working.

Eric Anholt
eric at anholt.net                         eric.anholt at intel.com

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