Merge tag 'hwlock-v4.8' of git://github.com/andersson/remoteproc

[deliverable/linux.git] / kernel / time / timer.c

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 8f29abeb8c4d5458cd518dfd8ef8800eeb4e8eac..cb9ab401e2d9cad40d1f1dc41e33d52642a5d6e2 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1925,9 +1925,15 @@ static void __sched do_usleep_range(unsigned long min, unsigned long max)
 }
 
 /**
- * usleep_range - Drop in replacement for udelay where wakeup is flexible
+ * usleep_range - Sleep for an approximate time
  * @min: Minimum time in usecs to sleep
  * @max: Maximum time in usecs to sleep
+ *
+ * In non-atomic context where the exact wakeup time is flexible, use
+ * usleep_range() instead of udelay().  The sleep improves responsiveness
+ * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces
+ * power usage by allowing hrtimers to take advantage of an already-
+ * scheduled interrupt instead of scheduling a new one just for this sleep.
  */
 void __sched usleep_range(unsigned long min, unsigned long max)
 {