[Bug 42035] no way to turn off vsync

[Michal Suchanek]

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.
>> >
>> > Thoughts
>>
>> Is it possible to determine if the option is on or off?
>>
>> Or does it produce some log messages saying what it enables based on what?
>
> You're welcome to try it yourself. ;) Anyway, the updated patch below shows
>
> (==) RADEON(0): SwapBuffers wait for vblank: dis/enabled
>
> in the log by default and
>
> (**) RADEON(0): Option "SwapbuffersWait" ("<value>")
> [...]
> (**) RADEON(0): SwapBuffers wait for vblank: dis/enabled
>
> when the option is set in a configuration file.

Thanks for the patch.

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.

Michal