Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6

* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm: Include the connector name in the output_poll_execute() debug message
  drm/radeon/kms: fix bug in r600_gpu_is_lockup
  drm/radeon/kms: reorder display resume to avoid problems
  drm/radeon/kms/evergreen: reset the grbm blocks at resume and init
  drm/radeon/kms: fix evergreen asic reset
  Revert "drm: Don't try and disable an encoder that was never enabled"
  drm/radeon: Add early unregister of firmware fb's
  drm/radeon: use aperture size not vram size for overlap tests
  drm/radeon/kms/evergreen: flush hdp cache when flushing gart tlb
  drm/radeon/kms: disable the r600 cb offset checker for linear surfaces
  drm/radeon/kms: disable ss fixed ref divide
  drm/i915/bios: Reverse order of 100/120 Mhz SSC clocks
  agp/intel: Fix missed cached memory flags setting in i965_write_entry()
  drm/i915/sdvo: Only use the SDVO pin if it is in the valid range
  drm/i915/ringbuffer: Handle wrapping of the autoreported HEAD
  drm/i915/dp: Fix I2C/EDID handling with active DisplayPort to DVI converter

1 files changed, 8 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 89a65be8a3f3..31cd7e33e820 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/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;