diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index 8deffcd..102ce96 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -185,6 +185,8 @@
 	hardware in the irq_set_freq function.  If it isn't, return -EINVAL.  If
 	you cannot actually change the frequency, do not define irq_set_freq.
 
+    *	RTC_PIE_ON, RTC_PIE_OFF: the irq_set_state function will be called.
+
 If all else fails, check out the rtc-test.c driver!