1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 157057c79ca3..6615ac7fa60a 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -73,6 +73,27 @@ static inline void backlight_unregister_fb(struct backlight_device *bd)
 }
 #endif /* CONFIG_FB */
 
+static void backlight_generate_event(struct backlight_device *bd,
+                                     enum backlight_update_reason reason)
+{
+        char *envp[2];
+
+        switch (reason) {
+        case BACKLIGHT_UPDATE_SYSFS:
+                envp[0] = "SOURCE=sysfs";
+                break;
+        case BACKLIGHT_UPDATE_HOTKEY:
+                envp[0] = "SOURCE=hotkey";
+                break;
+        default:
+                envp[0] = "SOURCE=unknown";
+                break;
+        }
+        envp[1] = NULL;
+        kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
+        sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
+}
+
 static ssize_t backlight_show_power(struct device *dev,
                 struct device_attribute *attr,char *buf)
 {
@@ -142,6 +163,8 @@ static ssize_t backlight_store_brightness(struct device *dev,
         }
         mutex_unlock(&bd->ops_lock);
 
+        backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
+
         return rc;
 }
 
@@ -214,6 +237,25 @@ static struct device_attribute bl_device_attributes[] = {
 };
 
 /**
+ * backlight_force_update - tell the backlight subsystem that hardware state
+ *   has changed
+ * @bd: the backlight device to update
+ *
+ * Updates the internal state of the backlight in response to a hardware event,
+ * and generate a uevent to notify userspace
+ */
+void backlight_force_update(struct backlight_device *bd,
+                            enum backlight_update_reason reason)
+{
+        mutex_lock(&bd->ops_lock);
+        if (bd->ops && bd->ops->get_brightness)
+                bd->props.brightness = bd->ops->get_brightness(bd);
+        mutex_unlock(&bd->ops_lock);
+        backlight_generate_event(bd, reason);
+}
+EXPORT_SYMBOL(backlight_force_update);
+
+/**
  * backlight_device_register - create and register a new object of
  *   backlight_device class.
  * @name: the name of the new object(must be the same as the name of the