Files
linux/drivers/gpu
Jiri Kosina 335b05e627 drm/i915: read HEAD register back in init_ring_common() to enforce ordering
commit ece4a17d23 upstream.

Withtout this, ring initialization fails reliabily during resume with

	[drm:init_ring_common] *ERROR* render ring initialization failed ctl 0001f001 head ffffff8804 tail 00000000 start 000e4000

This is not a complete fix, but it is verified to make the ring
initialization failures during resume much less likely.

We were not able to root-cause this bug (likely HW-specific to Gen4 chips)
yet. This is therefore used as a ducttape before problem is fully
understood and proper fix created, so that people don't suffer from
completely unusable systems in the meantime.

The discussion and debugging is happening at

	https://bugs.freedesktop.org/show_bug.cgi?id=76554

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-10-05 14:54:07 -07:00
..
2013-02-08 12:02:43 +10:00
2013-04-22 12:32:40 +02:00