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, 11 insertions, 38 deletions

diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index 3b6529392359..66462286e704 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2116,13 +2116,13 @@ static int atyfb_pci_resume(struct pci_dev *pdev)
 
 static struct backlight_properties aty_bl_data;
 
-/* Call with fb_info->bl_mutex held */
 static int aty_bl_get_level_brightness(struct atyfb_par *par, int level)
 {
         struct fb_info *info = pci_get_drvdata(par->pdev);
         int atylevel;
 
         /* Get and convert the value */
+        /* No locking of bl_curve since we read a single value */
         atylevel = info->bl_curve[level] * FB_BACKLIGHT_MAX / MAX_LEVEL;
 
         if (atylevel < 0)
@@ -2133,8 +2133,7 @@ static int aty_bl_get_level_brightness(struct atyfb_par *par, int level)
         return atylevel;
 }
 
-/* Call with fb_info->bl_mutex held */
-static int __aty_bl_update_status(struct backlight_device *bd)
+static int aty_bl_update_status(struct backlight_device *bd)
 {
         struct atyfb_par *par = class_get_devdata(&bd->class_dev);
         unsigned int reg = aty_ld_lcd(LCD_MISC_CNTL, par);
@@ -2159,19 +2158,6 @@ static int __aty_bl_update_status(struct backlight_device *bd)
         return 0;
 }
 
-static int aty_bl_update_status(struct backlight_device *bd)
-{
-        struct atyfb_par *par = class_get_devdata(&bd->class_dev);
-        struct fb_info *info = pci_get_drvdata(par->pdev);
-        int ret;
-
-        mutex_lock(&info->bl_mutex);
-        ret = __aty_bl_update_status(bd);
-        mutex_unlock(&info->bl_mutex);
-
-        return ret;
-}
-
 static int aty_bl_get_brightness(struct backlight_device *bd)
 {
         return bd->props->brightness;
@@ -2203,12 +2189,10 @@ static void aty_bl_init(struct atyfb_par *par)
                 goto error;
         }
 
-        mutex_lock(&info->bl_mutex);
         info->bl_dev = bd;
         fb_bl_default_curve(info, 0,
                 0x3F * FB_BACKLIGHT_MAX / MAX_LEVEL,
                 0xFF * FB_BACKLIGHT_MAX / MAX_LEVEL);
-        mutex_unlock(&info->bl_mutex);
 
         bd->props->brightness = aty_bl_data.max_brightness;
         bd->props->power = FB_BLANK_UNBLANK;
@@ -2229,30 +2213,19 @@ error:
         return;
 }
 
-static void aty_bl_exit(struct atyfb_par *par)
+static void aty_bl_exit(struct backlight_device *bd)
 {
-        struct fb_info *info = pci_get_drvdata(par->pdev);
-
+        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("aty: Backlight unloaded\n");
         }
-        mutex_unlock(&info->bl_mutex);
-
-#ifdef CONFIG_PMAC_BACKLIGHT
-        mutex_unlock(&pmac_backlight_mutex);
-#endif
 }
 
 #endif /* CONFIG_FB_ATY_BACKLIGHT */
@@ -3705,13 +3678,13 @@ static void __devexit atyfb_remove(struct fb_info *info)
         aty_set_crtc(par, &saved_crtc);
         par->pll_ops->set_pll(info, &saved_pll);
 
+        unregister_framebuffer(info);
+
 #ifdef CONFIG_FB_ATY_BACKLIGHT
         if (M64_HAS(MOBIL_BUS))
-                aty_bl_exit(par);
+                aty_bl_exit(info->bl_dev);
 #endif
 
-        unregister_framebuffer(info);
-
 #ifdef CONFIG_MTRR
         if (par->mtrr_reg >= 0) {
             mtrr_del(par->mtrr_reg, 0, 0);