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-rw-r--r--drivers/gpu/drm/i915/intel_ringbuffer.c19
-rw-r--r--drivers/gpu/drm/i915/intel_ringbuffer.h5
2 files changed, 11 insertions, 13 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;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 3126c2681983..d2cd0f1efeed 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/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;