X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=drivers%2Fgpu%2Fdrm%2Fi915%2Fintel_ringbuffer.c;h=4605c3877c955cc7374583df3b37784e1cd34056;hb=335b05e627c4ed007f2743f78d1cac60a265e74e;hp=629527d205de88dbe1463b9a127987ceafde9dc1;hpb=1fc3a6ed0203b772f02253be3aea606b7192d429;p=firefly-linux-kernel-4.4.55.git

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 629527d205de..4605c3877c95 100644
--- 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_ring_buffer *ring)
 		}
 	}
 
+	/* 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