[Linux-fbdev-devel] LCD: fix oops if driver only interested in .set_power

[Ben D. <ben...@fl...>]

The LCD driver core calls LCD drivers when either the
blanking state or the display mode has changed, but
does not make any check to see if the called driver
has a .set_mode method.

This means if a driver only has a .set_power method
then the system will OOPS on changing mode (and with
the console semaphore held so you cannot easily see
the problem).

Fix the problem by ensuring that either callback is
valid before calling it.

Signed-off-by: Ben Dooks <ben...@fl...>
Index: linux.git/drivers/video/backlight/lcd.c
===================================================================
--- linux.git.orig/drivers/video/backlight/lcd.c	2008-11-18 12:59:21.000000000 +0000
+++ linux.git/drivers/video/backlight/lcd.c	2008-11-18 15:07:25.000000000 +0000
@@ -43,9 +43,11 @@ static int fb_notifier_callback(struct n
 	mutex_lock(&ld->ops_lock);
 	if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
 		if (event == FB_EVENT_BLANK)
-			ld->ops->set_power(ld, *(int *)evdata->data);
+			if (ld->ops->set_power)
+				ld->ops->set_power(ld, *(int *)evdata->data);
 		else
-			ld->ops->set_mode(ld, evdata->data);
+			if (ld->ops->set_mode)
+				ld->ops->set_mode(ld, evdata->data);
 	}
 	mutex_unlock(&ld->ops_lock);
 	return 0;

-- 
Ben (be...@fl..., http://www.fluff.org/)

  'a smiley only costs 4 bytes'