Commits
Jiri Kosina committed ece4a17d237
drm/i915: read HEAD register back in init_ring_common() to enforce ordering 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> Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>