Vblanks, CRTCs and GLX, oh my!
Michel Dänzer
michel at tungstengraphics.com
Fri Sep 21 08:04:14 PDT 2007
On Fri, 2007-09-21 at 07:59 -0700, Jesse Barnes wrote:
> On Friday, September 21, 2007 2:51:02 am Michel Dänzer wrote:
> > > So:
> > > - use the vblank-rework tree to make per-CRTC vblank counters (as
> > > you
> > > say, this breaks some setups but will fix others)
> >
> > Out of curiosity, what setups are you thinking of that this will fix on
> > its own? Can't think of any offhand.
>
> It should fix the case where a client is waiting on pipe B when vblank
> interrupts on pipe A go from off to on. Currently, that'll cause the client
> to switch to the wrong vblank counter after pipe A's interrupts become
> active. In the vblank rework tree, it'll either not work in the first place
> (because it's using the wrong counter) or it'll work and keep working due to
> passing in DRM_VBLANK_SECONDARY. I think this is the correct
> behavior.
Unless I'm missing something, this would only be true if
xf86-video-intel ever enabled vblank interrupts for pipe B only, which
it doesn't (with a DRM that supports vblank interrupts on both pipes
independently). It always leaves them enabled for pipe A, even when pipe
A is actually disabled.
--
Earthling Michel Dänzer | http://tungstengraphics.com
Libre software enthusiast | Debian, X and DRI developer
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