[Bug 42035] no way to turn off vsync

[Michel Dänzer]

On Die, 2011-11-01 at 08:50 +0100, Michal Suchanek wrote:
> 2011/10/24 Michel Dänzer <michel at daenzer.net>:
> > On Mon, 2011-10-24 at 14:00 +0200, Michal Suchanek wrote:
> >> 2011/10/24 Michel Dänzer <michel at daenzer.net>:
> >> > On Don, 2011-10-20 at 12:16 +0200, Michal Suchanek wrote:
> >> >> On 20 October 2011 11:38,  <bugzilla-daemon at freedesktop.org> wrote:
> >> >> > https://bugs.freedesktop.org/show_bug.cgi?id=42035
> >> >> >
> >> >> > --- Comment #1 from Michel Dänzer <michel at daenzer.net> 2011-10-20 02:38:29 PDT ---
> >> >> >> This should be runtime configurable, preferably per-application like dri.
> >> >> >
> >> >> > That would require some xserver dri2 changes first, to allow the driver to tell
> >> >> > the different cases apart. There's been some discussion about this on the
> >> >> > xorg-devel list, started by Chris Wilson.
> >> >>
> >> >> Anyone can point at the discussion or say what the problem is with this?
> >> >
> >> > Actually, the radeon driver patch below might be good enough, at least
> >> > for now. It disables Option "SwapBuffersWait" by default when the real
> >> > sync-to-vblank functionality is working. There should be no need for the
> >> > vline waits for DRI2 in that case.

[...]

> I am using a X server with this patch applied now.
> 
> It merely picks a sensible default but it's quite helpful.
> 
> I could configure my X server to disable the vline sync but since it
> is not really helpful in its current state and per-application
> configurable replacement exists I guess this would be nice to have in
> the driver.

Actually, I'm not sure anymore it's a good idea, as it results e.g. in
horrible tearing with fullscreen video playback in compiz with multiple
monitors enabled. 

Also, I still can't see how having this option enabled can result in 3D
clients (only, as opposed to the whole X display) hanging. You'd need to
gather more information about that. 

Anyway, I'm not including this in the upcoming 6.14.3 driver release. We
can consider pushing it afterwards though for more testing. 


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