[Bug 42035] no way to turn off vsync

[Michel Dänzer]

On Mit, 2011-10-26 at 14:16 +0200, Michal Suchanek wrote: 
> 2011/10/26 Michel Dänzer <michel at daenzer.net>:
> > On Mit, 2011-10-26 at 12:05 +0200, Michal Suchanek wrote:
> >> 2011/10/26 Michel Dänzer <michel at daenzer.net>:
> >> > On Die, 2011-10-25 at 20:41 +0200, Michal Suchanek wrote:
> >> >> 2011/10/25 Michel Dänzer <michel at daenzer.net>:
> >> >> > On Mon, 2011-10-24 at 23:23 +0200, Michal Suchanek wrote:
> >> >> >> With this patch it should be at least possible to turn off all this
> >> >> >> when it does not work.
> >> >> >
> >> >> > Exactly. So, have you had a chance to try it?
> >> >>
> >> >> I installed the packages I built yesterday. The patch has no visible effect.
> >> >
> >> > Well, I do see an effect in the log file:
> >> >
> >> > [2558366.995] (==) RADEON(0): SwapBuffers wait for vblank: disabled
> >> >
> >> >
> >> >> > Does it address your bug report?
> >> >>
> >> >> I am not quite sure.
> >> >
> >> > The above means the thing the bug report complains about being
> >> > impossible to disable is disabled.
> >>
> >> Still it is disabled without the patch too, which it supposedly should not.
> >
> > I don't see how that can be the case with a driver built from unpatched
> > upstream, without (the equivalent of) Option "SwapbuffersWait" "off".
> 
> I don't have that in Xorg.conf and the only patch Ubuntu adds fixes up
> the -background none option.
> 
> So I would suspect that in this particular driver snapshot vblank is
> broken in entirely new way which completely evades whatever the patch
> is doing.

Option "SwapbuffersWait" has nothing to do with sync to vblank (which is
controlled via the driconf setting vblank_mode). It only controls
whether tearing is avoided for DRI2 buffer swaps without sync to vblank.


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer