1 files changed, 24 insertions, 25 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index b83306f9244..31cd7e33e82 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -156,23 +156,25 @@ static int init_ring_common(struct drm_device *dev,
 
         /* G45 ring initialization fails to reset head to zero */
         if (head != 0) {
-                DRM_ERROR("%s head not reset to zero "
-                                "ctl %08x head %08x tail %08x start %08x\n",
-                                ring->name,
-                                I915_READ_CTL(ring),
-                                I915_READ_HEAD(ring),
-                                I915_READ_TAIL(ring),
-                                I915_READ_START(ring));
+                DRM_DEBUG_KMS("%s head not reset to zero "
+                              "ctl %08x head %08x tail %08x start %08x\n",
+                              ring->name,
+                              I915_READ_CTL(ring),
+                              I915_READ_HEAD(ring),
+                              I915_READ_TAIL(ring),
+                              I915_READ_START(ring));
 
                 I915_WRITE_HEAD(ring, 0);
 
-                DRM_ERROR("%s head forced to zero "
-                                "ctl %08x head %08x tail %08x start %08x\n",
-                                ring->name,
-                                I915_READ_CTL(ring),
-                                I915_READ_HEAD(ring),
-                                I915_READ_TAIL(ring),
-                                I915_READ_START(ring));
+                if (I915_READ_HEAD(ring) & HEAD_ADDR) {
+                        DRM_ERROR("failed to set %s head to zero "
+                                  "ctl %08x head %08x tail %08x start %08x\n",
+                                  ring->name,
+                                  I915_READ_CTL(ring),
+                                  I915_READ_HEAD(ring),
+                                  I915_READ_TAIL(ring),
+                                  I915_READ_START(ring));
+                }
         }
 
         I915_WRITE_CTL(ring,
@@ -694,20 +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;