drm/msm: Avoid rounding up to one jiffy

If userspace is trying to achieve a timeout of zero, let 'em have it.
Only round up if the timeout is greater than zero.

Fixes: 4969bcc ("drm/msm: Avoid rounding down to zero jiffies")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/632264/

Author: robclark

drivers/gpu/drm/msm/msm_drv.h

@@ -537,15 +537,12 @@ static inline int align_pitch(int width, int bpp)
 static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
 {
 	ktime_t now = ktime_get();
-	s64 remaining_jiffies;
 
-	if (ktime_compare(*timeout, now) < 0) {
-		remaining_jiffies = 0;
-	} else {
-		ktime_t rem = ktime_sub(*timeout, now);
-		remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ);
-	}
+	if (ktime_compare(*timeout, now) <= 0)
+		return 0;
 
+	ktime_t rem = ktime_sub(*timeout, now);
+	s64 remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ);
 	return clamp(remaining_jiffies, 1LL, (s64)INT_MAX);
 }