[PATCH] ugly patch for DRM based XSync VBLANK support
Matthias Clasen
mclasen at redhat.com
Sun Mar 12 17:52:07 PST 2006
On Sat, 2006-03-11 at 14:11 -0800, Jesse Barnes wrote:
> Here's an ugly patch that attempts to add an XSync system counter called
> "VBLANK" to the server if the underlying drm driver that was just
> opened supports vblank signals. It doesn't work very well for a couple
> of reasons:
> o drmOpen is working ok (I get back a real fd) but drmWaitVBlank gives
> me EPERM instead of EINVAL like it should (my test machine doesn't
> have a drm driver with vblank support yet), so VBLANK support is
> disabled (IOW I haven't actually tested it :)
> o it's totally multihead ignorant
>
> Hopefully someone can clue me in about the first problem, and the second
> needs a bit more thought. It seems like there should be an XSync
> VBLANK counter per-screen, not per-drm and obviously not a single
> global one. It looks like the drm drivers could handle this, but it
> would make things harder for the clients since they'd have to dig
> through the system counters to find the VBLANK counter corresponding to
> their head (I guess via strmp?) which means a well defined namespace
> for the VBLANK XSync counters is necessary. Thoughts?
The established ICCCM convention for naming per-screen resources
is FOO_S<n>, where n is the screen number. Following that, you could
name the counter VBLANK_S0, VBLANK_S1,...
Matthias
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