backlight: Fix external uses of backlight internal semaphore

backlight_device->sem has a very specific use as documented in the
header file. The external users of this are using it for a different
reason, to serialise access to the update_status() method.

backlight users were supposed to implement their own internal
serialisation of update_status() if needed but everyone is doing
things differently and incorrectly. Therefore add a global mutex to
take care of serialisation for everyone, once and for all.

Locking for get_brightness remains optional since most users don't
need it.

Also update the lcd class in a similar way.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

1 files changed, 1 insertions, 5 deletions

diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c
index fd825711bb63..b70d18f7fcd9 100644
--- a/drivers/video/riva/fbdev.c
+++ b/drivers/video/riva/fbdev.c
@@ -357,10 +357,8 @@ static void riva_bl_set_power(struct fb_info *info, int power)
 	mutex_lock(&info->bl_mutex);
 
 	if (info->bl_dev) {
-		down(&info->bl_dev->sem);
 		info->bl_dev->props->power = power;
 		__riva_bl_update_status(info->bl_dev);
-		up(&info->bl_dev->sem);
 	}
 
 	mutex_unlock(&info->bl_mutex);
@@ -397,11 +395,9 @@ static void riva_bl_init(struct riva_par *par)
 		FB_BACKLIGHT_MAX);
 	mutex_unlock(&info->bl_mutex);
 
-	down(&bd->sem);
 	bd->props->brightness = riva_bl_data.max_brightness;
 	bd->props->power = FB_BLANK_UNBLANK;
-	bd->props->update_status(bd);
-	up(&bd->sem);
+	backlight_update_status(bd);
 
 #ifdef CONFIG_PMAC_BACKLIGHT
 	mutex_lock(&pmac_backlight_mutex);