drm/i915/bdw: poll semaphores
authorBen Widawsky <benjamin.widawsky@intel.com>
Mon, 30 Jun 2014 16:53:43 +0000 (09:53 -0700)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 7 Jul 2014 21:16:55 +0000 (23:16 +0200)
commitbae4fcd2c7b778a3f69e03e244221cd4932b8f67
tree5341467f3fc6f8c76d2dc822925b2c4e0c3606e2
parente04934cf256154fd6cc88a0767e45bd1b4920419
drm/i915/bdw: poll semaphores

As Ville points out, it's possible/probable we don't actually need this.
Potentially, this validates the letter of the spec, and not the spirit.

Ville:
> I discussed this on irc w/ Ben, and I was suggesting we don't need to
> poll. Polling apparently can be used as a workaround for certain
> hardware issues, but it looks like those issues shouldn't affect us,
> for the momemnt at least. So my suggestion was to try w/o polling
> first (since there could be some power cost to polling) and add the
> poll bit if problems arise.

Rodrigo: Spec suggests this as an W/A for GT3. However semaphores didn't
worked in my BDW GT2 on Signal Mode. So pool mode is definitely needed.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Tested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drivers/gpu/drm/i915/intel_ringbuffer.c