drm/i915/ringbuffer: set FORCE_WAKE bit before reading ring register
Before reading ring register, set FORCE_WAKE bit to prevent GT core
power down to low power state, otherwise we may read stale values.
Signed-off-by: Zou Nan hai <nanhai.zou@intel.com>
[ickle: added a udelay which seemed to do the trick on my SNB]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index f5d6151..99f2c96 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -708,7 +708,7 @@
int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
{
struct drm_device *dev = ring->dev;
- drm_i915_private_t *dev_priv = dev->dev_private;
+ struct drm_i915_private *dev_priv = dev->dev_private;
unsigned long end;
u32 head;