[PATCH v3 05/13] backlight: improve backlight_device documentation

[Sam Ravnborg <sam@ravnborg.org>]

Improve the documentation for backlight_device and
adapt it to kernel-doc style.

v2:
  - Add short intro to all fields (Daniel)
  - Updated description of update_lock (Daniel)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
---
 include/linux/backlight.h | 72 ++++++++++++++++++++++++++-------------
 1 file changed, 49 insertions(+), 23 deletions(-)

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 69a20da03035..cae1af95dd9d 100644
--- 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;
 };
 
-- 
2.25.1