2 files changed, 24 insertions, 17 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 51fbc5e33c55..6218fa97aa1e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -34,6 +34,14 @@
 #include "i915_trace.h"
 #include "intel_drv.h"
 
+static inline int ring_space(struct intel_ring_buffer *ring)
+{
+        int space = (ring->head & HEAD_ADDR) - (ring->tail + 8);
+        if (space < 0)
+                space += ring->size;
+        return space;
+}
+
 static u32 i915_gem_get_seqno(struct drm_device *dev)
 {
         drm_i915_private_t *dev_priv = dev->dev_private;
@@ -204,11 +212,9 @@ static int init_ring_common(struct intel_ring_buffer *ring)
         if (!drm_core_check_feature(ring->dev, DRIVER_MODESET))
                 i915_kernel_lost_context(ring->dev);
         else {
-                ring->head = I915_READ_HEAD(ring) & HEAD_ADDR;
+                ring->head = I915_READ_HEAD(ring);
                 ring->tail = I915_READ_TAIL(ring) & TAIL_ADDR;
-                ring->space = ring->head - (ring->tail + 8);
-                if (ring->space < 0)
-                        ring->space += ring->size;
+                ring->space = ring_space(ring);
         }
 
         return 0;
@@ -921,7 +927,7 @@ static int intel_wrap_ring_buffer(struct intel_ring_buffer *ring)
         }
 
         ring->tail = 0;
-        ring->space = ring->head - 8;
+        ring->space = ring_space(ring);
 
         return 0;
 }
@@ -933,20 +939,22 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
         unsigned long end;
         u32 head;
 
+        /* 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->head) {
+                ring->head = head;
+                ring->space = ring_space(ring);
+                if (ring->space >= n)
+                        return 0;
+        }
+
         trace_i915_ring_wait_begin (dev);
         end = jiffies + 3 * HZ;
         do {
-                /* 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;
+                ring->head = I915_READ_HEAD(ring);
+                ring->space = ring_space(ring);
                 if (ring->space >= n) {
                         trace_i915_ring_wait_end(dev);
                         return 0;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 61d5220c4b58..6d6fde85a636 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -47,7 +47,6 @@ struct  intel_ring_buffer {
         struct          drm_device *dev;
         struct          drm_i915_gem_object *obj;
 
-        u32             actual_head;
         u32             head;
         u32             tail;
         int             space;