diff --git a/drivers/staging/comedi/drivers/amplc_dio200_common.c b/drivers/staging/comedi/drivers/amplc_dio200_common.c
index 071d2fb4d7d0..f6e4e984235d 100644
--- a/drivers/staging/comedi/drivers/amplc_dio200_common.c
+++ b/drivers/staging/comedi/drivers/amplc_dio200_common.c
@@ -101,7 +101,7 @@ struct dio200_subdev_8255 {
 };
 
 struct dio200_subdev_intr {
-	spinlock_t spinlock;
+	spinlock_t spinlock;	/* protects the 'active' flag */
 	unsigned int ofs;
 	unsigned int valid_isns;
 	unsigned int enabled_isns;