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, 13 insertions, 37 deletions

diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c
index 9e7d3fcde207..ab00350907dd 100644
--- a/drivers/video/riva/fbdev.c
+++ b/drivers/video/riva/fbdev.c
@@ -282,7 +282,6 @@ static const struct riva_regs reg_template = {
 
 static struct backlight_properties riva_bl_data;
 
-/* Call with fb_info->bl_mutex held */
 static int riva_bl_get_level_brightness(struct riva_par *par,
                 int level)
 {
@@ -290,6 +289,7 @@ static int riva_bl_get_level_brightness(struct riva_par *par,
         int nlevel;
 
         /* Get and convert the value */
+        /* No locking on bl_curve since accessing a single value */
         nlevel = MIN_LEVEL + info->bl_curve[level] * LEVEL_STEP;
 
         if (nlevel < 0)
@@ -302,8 +302,7 @@ static int riva_bl_get_level_brightness(struct riva_par *par,
         return nlevel;
 }
 
-/* Call with fb_info->bl_mutex held */
-static int __riva_bl_update_status(struct backlight_device *bd)
+static int riva_bl_update_status(struct backlight_device *bd)
 {
         struct riva_par *par = class_get_devdata(&bd->class_dev);
         U032 tmp_pcrt, tmp_pmc;
@@ -328,19 +327,6 @@ static int __riva_bl_update_status(struct backlight_device *bd)
         return 0;
 }
 
-static int riva_bl_update_status(struct backlight_device *bd)
-{
-        struct riva_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 = __riva_bl_update_status(bd);
-        mutex_unlock(&info->bl_mutex);
-
-        return ret;
-}
-
 static int riva_bl_get_brightness(struct backlight_device *bd)
 {
         return bd->props->brightness;
@@ -376,12 +362,10 @@ static void riva_bl_init(struct riva_par *par)
                 goto error;
         }
 
-        mutex_lock(&info->bl_mutex);
         info->bl_dev = bd;
         fb_bl_default_curve(info, 0,
                 MIN_LEVEL * FB_BACKLIGHT_MAX / MAX_LEVEL,
                 FB_BACKLIGHT_MAX);
-        mutex_unlock(&info->bl_mutex);
 
         bd->props->brightness = riva_bl_data.max_brightness;
         bd->props->power = FB_BLANK_UNBLANK;
@@ -402,34 +386,25 @@ error:
         return;
 }
 
-static void riva_bl_exit(struct riva_par *par)
+static void riva_bl_exit(struct fb_info *info)
 {
-        struct fb_info *info = pci_get_drvdata(par->pdev);
+        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("riva: Backlight unloaded\n");
         }
-        mutex_unlock(&info->bl_mutex);
-
-#ifdef CONFIG_PMAC_BACKLIGHT
-        mutex_unlock(&pmac_backlight_mutex);
-#endif
 }
 #else
 static inline void riva_bl_init(struct riva_par *par) {}
-static inline void riva_bl_exit(struct riva_par *par) {}
+static inline void riva_bl_exit(struct fb_info *info) {}
 #endif /* CONFIG_FB_RIVA_BACKLIGHT */
 
 /* ------------------------------------------------------------------------- *
@@ -2146,14 +2121,15 @@ static void __exit rivafb_remove(struct pci_dev *pd)
         
         NVTRACE_ENTER();
 
-        riva_bl_exit(par);
-
 #ifdef CONFIG_FB_RIVA_I2C
         riva_delete_i2c_busses(par);
         kfree(par->EDID);
 #endif
 
         unregister_framebuffer(info);
+
+        riva_bl_exit(info);
+
 #ifdef CONFIG_MTRR
         if (par->mtrr.vram_valid)
                 mtrr_del(par->mtrr.vram, info->fix.smem_start,