drm/i915: Apply HWSTAM workaround for BSD ring on SandyBridge

[deliverable/linux.git] / drivers / gpu / drm / i915 / i915_irq.c

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b9fafe3b045bda5817047f2a5cde8a6fc1b58265..ae2b49969b995c0b1c7f7f76f65d2426ea003522 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1740,6 +1740,17 @@ void ironlake_irq_preinstall(struct drm_device *dev)
                INIT_WORK(&dev_priv->rps_work, gen6_pm_rps_work);
 
        I915_WRITE(HWSTAM, 0xeffe);
+       if (IS_GEN6(dev)) {
+               /* Workaround stalls observed on Sandy Bridge GPUs by
+                * making the blitter command streamer generate a
+                * write to the Hardware Status Page for
+                * MI_USER_INTERRUPT.  This appears to serialize the
+                * previous seqno write out before the interrupt
+                * happens.
+                */
+               I915_WRITE(GEN6_BLITTER_HWSTAM, ~GEN6_BLITTER_USER_INTERRUPT);
+               I915_WRITE(GEN6_BSD_HWSTAM, ~GEN6_BSD_USER_INTERRUPT);
+       }
 
        /* XXX hotplug from PCH */