From 6e9490a87be3411d865e5c2f521c4da0bdd608c2 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Wed, 17 Sep 2014 14:48:31 -0700 Subject: [PATCH] 3.10-stable patches added patches: drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch --- ...init_ring_common-to-enforce-ordering.patch | 45 +++++++++++++++++++ queue-3.10/series | 1 + 2 files changed, 46 insertions(+) create mode 100644 queue-3.10/drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch diff --git a/queue-3.10/drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch b/queue-3.10/drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch new file mode 100644 index 00000000000..90308298981 --- /dev/null +++ b/queue-3.10/drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch @@ -0,0 +1,45 @@ +From ece4a17d237a79f63fbfaf3f724a12b6d500555c Mon Sep 17 00:00:00 2001 +From: Jiri Kosina +Date: Thu, 7 Aug 2014 16:29:53 +0200 +Subject: drm/i915: read HEAD register back in init_ring_common() to enforce ordering + +From: Jiri Kosina + +commit ece4a17d237a79f63fbfaf3f724a12b6d500555c 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 +Signed-off-by: Daniel Vetter +Signed-off-by: Greg Kroah-Hartman + +--- + drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++ + 1 file changed, 3 insertions(+) + +--- a/drivers/gpu/drm/i915/intel_ringbuffer.c ++++ b/drivers/gpu/drm/i915/intel_ringbuffer.c +@@ -396,6 +396,9 @@ static int init_ring_common(struct intel + } + } + ++ /* Enforce ordering by reading HEAD register back */ ++ I915_READ_HEAD(ring); ++ + /* Initialize the ring. This must happen _after_ we've cleared the ring + * registers with the above sequence (the readback of the HEAD registers + * also enforces ordering), otherwise the hw might lose the new ring diff --git a/queue-3.10/series b/queue-3.10/series index 750efe287ad..f5f97dd4079 100644 --- a/queue-3.10/series +++ b/queue-3.10/series @@ -8,3 +8,4 @@ drm-tilcdc-fix-double-kfree.patch drm-ttm-fix-possible-division-by-0-in-ttm_dma_pool_shrink_scan.patch drm-ttm-choose-a-pool-to-shrink-correctly-in-ttm_dma_pool_shrink_scan.patch drm-radeon-load-the-lm63-driver-for-an-lm64-thermal-chip.patch +drm-i915-read-head-register-back-in-init_ring_common-to-enforce-ordering.patch -- 2.47.3