1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/input.h b/include/linux/input.h
index 0ccfc30cd40f..c2b1a7d244d9 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -1377,6 +1377,10 @@ extern struct class input_class;
  * methods; erase() is optional. set_gain() and set_autocenter() need
  * only be implemented if driver sets up FF_GAIN and FF_AUTOCENTER
  * bits.
+ *
+ * Note that playback(), set_gain() and set_autocenter() are called with
+ * dev->event_lock spinlock held and interrupts off and thus may not
+ * sleep.
  */
 struct ff_device {
         int (*upload)(struct input_dev *dev, struct ff_effect *effect,