backlight: backlight: Improve backlight_device documentation

[linux-2.6-microblaze.git] / include / linux / backlight.h

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 3554aef..cf99771 100644 (file)
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -14,21 +14,6 @@
 #include <linux/mutex.h>
 #include <linux/notifier.h>
 
-/* Notes on locking:
- *
- * backlight_device->ops_lock is an internal backlight lock protecting the
- * ops pointer and no code outside the core should need to touch it.
- *
- * Access to update_status() is serialised by the update_lock mutex since
- * most drivers seem to need this and historically get it wrong.
- *
- * Most drivers don't need locking on their get_brightness() method.
- * If yours does, you need to implement it in the driver. You can use the
- * update_lock mutex if appropriate.
- *
- * Any other use of the locks below is probably wrong.
- */
-
 enum backlight_update_reason {
        BACKLIGHT_UPDATE_HOTKEY,
        BACKLIGHT_UPDATE_SYSFS,
@@ -215,30 +200,71 @@ struct backlight_properties {
        enum backlight_scale scale;
 };
 
+/**
+ * struct backlight_device - backlight device data
+ *
+ * This structure holds all data required by a backlight device.
+ */
 struct backlight_device {
-       /* Backlight properties */
+       /**
+        * @props: Backlight properties
+        */
        struct backlight_properties props;
 
-       /* Serialise access to update_status method */
+       /**
+        * @update_lock: The lock used when calling the update_status() operation.
+        *
+        * update_lock is an internal backlight lock that serialise access
+        * to the update_status() operation. The backlight core holds the update_lock
+        * when calling the update_status() operation. The update_lock shall not
+        * be used by backlight drivers.
+        */
        struct mutex update_lock;
 
-       /* This protects the 'ops' field. If 'ops' is NULL, the driver that
-          registered this device has been unloaded, and if class_get_devdata()
-          points to something in the body of that driver, it is also invalid. */
+       /**
+        * @ops_lock: The lock used around everything related to backlight_ops.
+        *
+        * ops_lock is an internal backlight lock that protects the ops pointer
+        * and is used around all accesses to ops and when the operations are
+        * invoked. The ops_lock shall not be used by backlight drivers.
+        */
        struct mutex ops_lock;
+
+       /**
+        * @ops: Pointer to the backlight operations.
+        *
+        * If ops is NULL, the driver that registered this device has been unloaded,
+        * and if class_get_devdata() points to something in the body of that driver,
+        * it is also invalid.
+        */
        const struct backlight_ops *ops;
 
-       /* The framebuffer notifier block */
+       /**
+        * @fb_notif: The framebuffer notifier block
+        */
        struct notifier_block fb_notif;
 
-       /* list entry of all registered backlight devices */
+       /**
+        * @entry: List entry of all registered backlight devices
+        */
        struct list_head entry;
 
+       /**
+        * @dev: Parent device.
+        */
        struct device dev;
 
-       /* Multiple framebuffers may share one backlight device */
+       /**
+        * @fb_bl_on: The state of individual fbdev's.
+        *
+        * Multiple fbdev's may share one backlight device. The fb_bl_on
+        * records the state of the individual fbdev.
+        */
        bool fb_bl_on[FB_MAX];
 
+       /**
+        * @use_count: The number of uses of fb_bl_on.
+        */
        int use_count;
 };