[PATCH 3.0-rc3, v2] i915: Fix gen6 (SNB) GPU stalling

From: Daniel J Blueman
Date: Fri Jun 17 2011 - 12:42:59 EST

Workaround Sandy Bridge GPU stalls by allowing the blitter command streamer
to write interrupt state to the Hardware Status Page when a MI_USER_INTERRUPT
command is decoded.

v1->v2: Moved to prior interrupt handler installation and RMW flags as per

Eric, if you're happy, please sign-off and send to Dave for inclusion in -rc4
if possible. Further changes may be needed for -stable.

Signed-off-by: Daniel J Blueman <daniel.blueman@xxxxxxxxx>
drivers/gpu/drm/i915/i915_irq.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b9fafe3..b7f11a5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1741,6 +1741,13 @@ void ironlake_irq_preinstall(struct drm_device *dev)

I915_WRITE(HWSTAM, 0xeffe);

+ if (IS_GEN6(dev))
+ /* workaround stalls observed on Sandy Bridge GPUs by
+ allowing the blitter command streamer to generate a
+ write to the Hardware Status Page for MI_USER_INTERRUPT */
/* XXX hotplug from PCH */

I915_WRITE(DEIMR, 0xffffffff);

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