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, 9 insertions, 5 deletions

diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c
index 818fb09105f9..40c80c8190e2 100644
--- a/drivers/video/fbsysfs.c
+++ b/drivers/video/fbsysfs.c
@@ -59,7 +59,7 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
         info->device = dev;
 
 #ifdef CONFIG_FB_BACKLIGHT
-        mutex_init(&info->bl_mutex);
+        mutex_init(&info->bl_curve_mutex);
 #endif
 
         return info;
@@ -445,10 +445,10 @@ static ssize_t store_bl_curve(struct device *device,
         /* If there has been an error in the input data, we won't
          * reach this loop.
          */
-        mutex_lock(&fb_info->bl_mutex);
+        mutex_lock(&fb_info->bl_curve_mutex);
         for (i = 0; i < FB_BACKLIGHT_LEVELS; ++i)
                 fb_info->bl_curve[i] = tmp_curve[i];
-        mutex_unlock(&fb_info->bl_mutex);
+        mutex_unlock(&fb_info->bl_curve_mutex);
 
         return count;
 }
@@ -466,7 +466,7 @@ static ssize_t show_bl_curve(struct device *device,
         if (!fb_info || !fb_info->bl_dev)
                 return -ENODEV;
 
-        mutex_lock(&fb_info->bl_mutex);
+        mutex_lock(&fb_info->bl_curve_mutex);
         for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8)
                 len += snprintf(&buf[len], PAGE_SIZE,
                                 "%02x %02x %02x %02x %02x %02x %02x %02x\n",
@@ -478,7 +478,7 @@ static ssize_t show_bl_curve(struct device *device,
                                 fb_info->bl_curve[i + 5],
                                 fb_info->bl_curve[i + 6],
                                 fb_info->bl_curve[i + 7]);
-        mutex_unlock(&fb_info->bl_mutex);
+        mutex_unlock(&fb_info->bl_curve_mutex);
 
         return len;
 }
@@ -552,6 +552,8 @@ void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)
 {
         unsigned int i, flat, count, range = (max - min);
 
+        mutex_lock(&fb_info->bl_curve_mutex);
+
         fb_info->bl_curve[0] = off;
 
         for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)
@@ -560,6 +562,8 @@ void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)
         count = FB_BACKLIGHT_LEVELS * 15 / 16;
         for (i = 0; i < count; ++i)
                 fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count);
+
+        mutex_unlock(&fb_info->bl_curve_mutex);
 }
 EXPORT_SYMBOL_GPL(fb_bl_default_curve);
 #endif