backlight: Rework backlight/fb interaction simplifying, lots

fb_info->bl_mutex is badly thought out and the backlight class doesn't
need it if the framebuffer/backlight register/unregister order is
consistent, particularly after the backlight locking fixes.

Fix the drivers to use the order:

backlight_device_register()
register_framebuffer()
unregister_framebuffer()
backlight_device_unregister()

and turn bl_mutex into a lock for the bl_curve data only.

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

1 files changed, 8 insertions, 21 deletions

diff --git a/drivers/video/aty/radeon_backlight.c b/drivers/video/aty/radeon_backlight.c
index 9cfcecac8b5..f94e4616788 100644
--- a/drivers/video/aty/radeon_backlight.c
+++ b/drivers/video/aty/radeon_backlight.c
@@ -29,17 +29,13 @@ struct radeon_bl_privdata {
 static int radeon_bl_get_level_brightness(struct radeon_bl_privdata *pdata,
 		int level)
 {
-	struct fb_info *info = pdata->rinfo->info;
 	int rlevel;
 
-	mutex_lock(&info->bl_mutex);
-
 	/* Get and convert the value */
+	/* No locking of bl_curve since we read a single value */
 	rlevel = pdata->rinfo->info->bl_curve[level] *
 		 FB_BACKLIGHT_MAX / MAX_RADEON_LEVEL;
 
-	mutex_unlock(&info->bl_mutex);
-
 	if (rlevel < 0)
 		rlevel = 0;
 	else if (rlevel > MAX_RADEON_LEVEL)
@@ -187,12 +183,10 @@ void radeonfb_bl_init(struct radeonfb_info *rinfo)
 		machine_is_compatible("PowerBook6,5");
 #endif
 
-	mutex_lock(&rinfo->info->bl_mutex);
 	rinfo->info->bl_dev = bd;
 	fb_bl_default_curve(rinfo->info, 0,
 		 63 * FB_BACKLIGHT_MAX / MAX_RADEON_LEVEL,
 		217 * FB_BACKLIGHT_MAX / MAX_RADEON_LEVEL);
-	mutex_unlock(&rinfo->info->bl_mutex);
 
 	bd->props->brightness = radeon_bl_data.max_brightness;
 	bd->props->power = FB_BLANK_UNBLANK;
@@ -216,29 +210,22 @@ error:
 
 void radeonfb_bl_exit(struct radeonfb_info *rinfo)
 {
-#ifdef CONFIG_PMAC_BACKLIGHT
-	mutex_lock(&pmac_backlight_mutex);
-#endif
+	struct backlight_device *bd = rinfo->info->bl_dev;
 
-	mutex_lock(&rinfo->info->bl_mutex);
-	if (rinfo->info->bl_dev) {
+	if (bd) {
 		struct radeon_bl_privdata *pdata;
 
 #ifdef CONFIG_PMAC_BACKLIGHT
-		if (pmac_backlight == rinfo->info->bl_dev)
+		mutex_lock(&pmac_backlight_mutex);
+		if (pmac_backlight == bd)
 			pmac_backlight = NULL;
+		mutex_unlock(&pmac_backlight_mutex);
 #endif
-
-		pdata = class_get_devdata(&rinfo->info->bl_dev->class_dev);
-		backlight_device_unregister(rinfo->info->bl_dev);
+		pdata = class_get_devdata(&bd->class_dev);
+		backlight_device_unregister(bd);
 		kfree(pdata);
 		rinfo->info->bl_dev = NULL;
 
 		printk("radeonfb: Backlight unloaded\n");
 	}
-	mutex_unlock(&rinfo->info->bl_mutex);
-
-#ifdef CONFIG_PMAC_BACKLIGHT
-	mutex_unlock(&pmac_backlight_mutex);
-#endif
 }