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, 32 deletions

diff --git a/drivers/video/nvidia/nv_backlight.c b/drivers/video/nvidia/nv_backlight.c
index 695b6bf54d92..2bebfeeb4f1d 100644
--- a/drivers/video/nvidia/nv_backlight.c
+++ b/drivers/video/nvidia/nv_backlight.c
@@ -30,7 +30,6 @@
 
 static struct backlight_properties nvidia_bl_data;
 
-/* Call with fb_info->bl_mutex held */
 static int nvidia_bl_get_level_brightness(struct nvidia_par *par,
                 int level)
 {
@@ -38,6 +37,7 @@ static int nvidia_bl_get_level_brightness(struct nvidia_par *par,
         int nlevel;
 
         /* Get and convert the value */
+        /* No locking of bl_curve since we read a single value */
         nlevel = MIN_LEVEL + info->bl_curve[level] * LEVEL_STEP;
 
         if (nlevel < 0)
@@ -50,8 +50,7 @@ static int nvidia_bl_get_level_brightness(struct nvidia_par *par,
         return nlevel;
 }
 
-/* Call with fb_info->bl_mutex held */
-static int __nvidia_bl_update_status(struct backlight_device *bd)
+static int nvidia_bl_update_status(struct backlight_device *bd)
 {
         struct nvidia_par *par = class_get_devdata(&bd->class_dev);
         u32 tmp_pcrt, tmp_pmc, fpcontrol;
@@ -85,19 +84,6 @@ static int __nvidia_bl_update_status(struct backlight_device *bd)
         return 0;
 }
 
-static int nvidia_bl_update_status(struct backlight_device *bd)
-{
-        struct nvidia_par *par = class_get_devdata(&bd->class_dev);
-        struct fb_info *info = pci_get_drvdata(par->pci_dev);
-        int ret;
-
-        mutex_lock(&info->bl_mutex);
-        ret = __nvidia_bl_update_status(bd);
-        mutex_unlock(&info->bl_mutex);
-
-        return ret;
-}
-
 static int nvidia_bl_get_brightness(struct backlight_device *bd)
 {
         return bd->props->brightness;
@@ -133,12 +119,10 @@ void nvidia_bl_init(struct nvidia_par *par)
                 goto error;
         }
 
-        mutex_lock(&info->bl_mutex);
         info->bl_dev = bd;
         fb_bl_default_curve(info, 0,
                 0x158 * FB_BACKLIGHT_MAX / MAX_LEVEL,
                 0x534 * FB_BACKLIGHT_MAX / MAX_LEVEL);
-        mutex_unlock(&info->bl_mutex);
 
         bd->props->brightness = nvidia_bl_data.max_brightness;
         bd->props->power = FB_BLANK_UNBLANK;
@@ -162,25 +146,17 @@ error:
 void nvidia_bl_exit(struct nvidia_par *par)
 {
         struct fb_info *info = pci_get_drvdata(par->pci_dev);
+        struct backlight_device *bd = info->bl_dev;
 
+        if (bd) {
 #ifdef CONFIG_PMAC_BACKLIGHT
-        mutex_lock(&pmac_backlight_mutex);
-#endif
-
-        mutex_lock(&info->bl_mutex);
-        if (info->bl_dev) {
-#ifdef CONFIG_PMAC_BACKLIGHT
-                if (pmac_backlight == info->bl_dev)
+                mutex_lock(&pmac_backlight_mutex);
+                if (pmac_backlight == bd)
                         pmac_backlight = NULL;
+                mutex_unlock(&pmac_backlight_mutex);
 #endif
-
-                backlight_device_unregister(info->bl_dev);
+                backlight_device_unregister(bd);
 
                 printk("nvidia: Backlight unloaded\n");
         }
-        mutex_unlock(&info->bl_mutex);
-
-#ifdef CONFIG_PMAC_BACKLIGHT
-        mutex_unlock(&pmac_backlight_mutex);
-#endif
 }