[PATCH] drm/msm: Avoid rounding down to zero jiffies

[Rob Clark]

From: Rob Clark <robdclark at chromium.org>

If userspace asked for a timeout greater than zero, but less than a
jiffy, they clearly weren't planning on spinning.  So it is better
to round up to one.

This fixes an issue with supertuxkart that was (for some reason)
spinning on a gl sync with 1ms timeout.  CPU time for a demo lap
drops from:

  15.83user 20.98system 0:47.46elapsed 77%CPU

to:

  8.84user 2.30system 0:46.67elapsed 23%CPU

Signed-off-by: Rob Clark <robdclark at chromium.org>
---
 drivers/gpu/drm/msm/msm_drv.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 9f0c184b02a0..7936aa6cad03 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -548,7 +548,7 @@ static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
 		remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ);
 	}
 
-	return clamp(remaining_jiffies, 0LL, (s64)INT_MAX);
+	return clamp(remaining_jiffies, 1LL, (s64)INT_MAX);
 }
 
 /* Driver helpers */
-- 
2.39.2