From: Barry Scott <barry.scott@on...> - 2006-02-13 18:02:19
I want to use DRM_IOCTL_WAIT_VBLANK ioctl in my X11 app that needs to
sync to the vertical retrace. But I've not managed to find docs on the
Are there docs? Can you point me to them please?
If not how do I use this ioctl?
On Monday 13 February 2006 13:02, Barry Scott wrote:
> I want to use DRM_IOCTL_WAIT_VBLANK ioctl in my X11 app that needs to
> sync to the vertical retrace. But I've not managed to find docs on the
> API yet.
> Are there docs? Can you point me to them please?
> If not how do I use this ioctl?
There aren't. You'd use a drmCommand ioctl, same as the DRI drivers do. S=
the i915 or radeon source for examples.
Also if you're trying to sync core X drawing with vblank you're unlikely to=
get consistent results by doing this in the app, since once you wait for=20
vblank you still need to flush all your rendering commands out to the serve=
which could very easily decide to schedule someone else ahead of you, or=20
could be swapped out, or could just take more than the retrace interval to=
finish rendering. The only reason it works for the DRI drivers is because=
they submit their own rendering commands directly to the card so there's le=
of a timing issue.