---

yaml
---
r: 223524
b: refs/heads/master
c: 8c0a6bf
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8316f33766a82907c694267ff911e45e256f09f9
+refs/heads/master: 8c0a6bfef165ccdbf5d73afb9dd660107b0c98d5

trunk/drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -696,20 +696,17 @@ int intel_wait_ring_buffer(struct drm_device *dev,
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	u32 head;
 
-	head = intel_read_status_page(ring, 4);
-	if (head) {
-		ring->head = head & HEAD_ADDR;
-		ring->space = ring->head - (ring->tail + 8);
-		if (ring->space < 0)
-			ring->space += ring->size;
-		if (ring->space >= n)
-			return 0;
-	}
-
 	trace_i915_ring_wait_begin (dev);
 	end = jiffies + 3 * HZ;
 	do {
-		ring->head = I915_READ_HEAD(ring) & HEAD_ADDR;
+		/* If the reported head position has wrapped or hasn't advanced,
+		 * fallback to the slow and accurate path.
+		 */
+		head = intel_read_status_page(ring, 4);
+		if (head < ring->actual_head)
+			head = I915_READ_HEAD(ring);
+		ring->actual_head = head;
+		ring->head = head & HEAD_ADDR;
 		ring->space = ring->head - (ring->tail + 8);
 		if (ring->space < 0)
 			ring->space += ring->size;

trunk/drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -30,8 +30,9 @@ struct  intel_ring_buffer {
 	struct		drm_device *dev;
 	struct		drm_gem_object *gem_object;
 
-	unsigned int	head;
-	unsigned int	tail;
+	u32		actual_head;
+	u32		head;
+	u32		tail;
 	int		space;
 	struct intel_hw_status_page status_page;