[Intel-gfx] [PATCH] drm/i915: use hrtimer in wait for vblank

[Arun R Murthy]

In wait for vblank use usleep_range, which will use hrtimers instead of
msleep. Using msleep(1~20) there are more chances of sleeping for 20ms.
Using usleep_range uses hrtimers and hence are precise, worst case will
trigger an interrupt at the higher/max timeout.

Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
---
 drivers/gpu/drm/i915/intel_drv.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 44067bc..079280a 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -52,7 +52,7 @@
 			break;						\
 		}							\
 		if (W && drm_can_sleep())  {				\
-			msleep(W);					\
+			usleep_range(W * 1000, W * 2 * 1000);		\
 		} else {						\
 			cpu_relax();					\
 		}							\
-- 
1.7.9.5