1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/parport.h b/include/linux/parport.h
index d2a4d9e1e6d1..f67f838a3a1f 100644
--- a/include/linux/parport.h
+++ b/include/linux/parport.h
@@ -236,7 +236,8 @@ struct pardevice {
 
 /* IEEE1284 information */
 
-/* IEEE1284 phases */
+/* IEEE1284 phases. These are exposed to userland through ppdev IOCTL
+ * PP[GS]ETPHASE, so do not change existing values. */
 enum ieee1284_phase {
         IEEE1284_PH_FWD_DATA,
         IEEE1284_PH_FWD_IDLE,