[Intel-gfx] Vblank timestamping improvements/fixes for Linux drm.
mario.kleiner.de at gmail.com
Sat Oct 26 10:27:38 CEST 2013
this patch set for the kernel pushes the latency sensitive bits of
vblank scanoutpos timestamping from the drm core into the kms drivers.
A change in the locking of the intel-kms driver for Linux 3.11 made
the old approach too inaccurate and also incompatible with the
PREEMPT_RT realtime kernel patch set. These patches fix that problem
and restore the old level of precision and reliability.
The patch set changes the prototype of driver->get_scanout_position()
to require/allow kms drivers to perform the ktime_get() system time
queries which go along with actual scanout position readout in a way
that provides maximum precision and to return those timestamps to
the drm. It also converts the only two kms drivers which use this api
so far (intel-kms and radeon-kms) to the new api and improves precision
and reliability of the intel-kms a lot.
Patches have been tested on Intel and AMD Radeon hardware and the Intel
bits have received some review and feedback by Ville Syrjälä.
Please review and apply if possible.
More information about the Intel-gfx