Faced with sporadic machine hangs on gen7, that mimic the issue of
concurrent writes to the same cacheline and seem to start with
commit 9b9ed309 (drm/i915: Remove forcewake dance from seqno/irq
barrier on legacy gen6+), let us restore the spinlock around the mmio
read.
Fixes: 9b9ed3093613288247a27a55a6dd07f1222150f1
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@intel.com>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c
b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 66f69cdd1d36..ad5bd3808d8b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1590,7 +1590,10 @@ gen6_seqno_barrier(struct intel_engine_cs *engine)
* interrupt (with the same net latency).
*/
struct drm_i915_private *dev_priv = engine->dev->dev_private;
+
+ spin_lock_irq(&dev_priv->uncore.lock);
POSTING_READ_FW(RING_ACTHD(engine->mmio_base));
+ spin_unlock_irq(&dev_priv->uncore.lock);
}
static u32
--
2.8.1
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