rtc: update documentation wrt irq_set_freq

Document the proper use of the irq_set_freq function.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index e20b19c..804a7cf 100644 (file)
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -182,8 +182,8 @@ driver returns ENOIOCTLCMD.  Some common examples:
        since the frequency is stored in the irq_freq member of the rtc_device
        structure.  Your driver needs to initialize the irq_freq member during
        init.  Make sure you check the requested frequency is in range of your
-       hardware in the irq_set_freq function.  If you cannot actually change
-       the frequency, just return -ENOTTY.
+       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.
 
 If all else fails, check out the rtc-test.c driver!