[PATCH v4 14/14] media: Clarify v4l2-async subdevice addition API

@@ -201,11 +201,42 @@ Before registering the notifier, bridge drivers must do two things:
 first, the notifier must be initialized using the
 :c:func:`v4l2_async_notifier_init`. Second, bridge drivers can then
 begin to form a list of subdevice descriptors that the bridge device
-needs for its operation. Subdevice descriptors are added to the notifier
-using the :c:func:`v4l2_async_notifier_add_subdev` call. This function
-takes two arguments: a pointer to struct :c:type:`v4l2_async_notifier`,
-and a pointer to the subdevice descripter, which is of type struct
-:c:type:`v4l2_async_subdev`.
+needs for its operation. Several functions are available, to add subdevice
+descriptors to a notifier, depending on the type of device and the needs of the
+driver.
+
+:c:func:`v4l2_async_register_subdev_sensor_common` is a helper function for
+sensor drivers registering their own async sub-device, but it also supports
+registering lens and flash devices. The function registers an async notifier for
+the sub-device which is unregistered with the async sub-device.
+
+:c:func:`v4l2_async_notifier_add_fwnode_remote_subdev`,
+:c:func:`v4l2_async_notifier_add_fwnode_subdev` and
+:c:func:`v4l2_async_notifier_add_i2c_subdev` are for bridge and ISP drivers for
+registering their async sub-devices.
+
+These functions allocate an async sub-device descriptor which is of type struct
+:c:type:`v4l2_async_subdev` embedded in a driver-specific struct. The &struct
+:c:type:`v4l2_async_subdev` shall be the first member of this struct:
+
+.. code-block:: c
+
+	struct my_async_subdev {
+		struct v4l2_async_subdev asd;
+		...
+	};
+
+	struct my_async_subdev *my_asd;
+	struct fwnode_handle *ep;
+
+	...
+
+	my_asd = v4l2_async_notifier_add_fwnode_remote_subdev(&notifier, ep,
+							      struct my_async_subdev);
+	fwnode_handle_put(ep);
+
+	if (IS_ERR(asd))
+		return PTR_ERR(asd);
 
 The V4L2 core will then use these descriptors to match asynchronously
 registered subdevices to them. If a match is detected the ``.bound()``

@@ -128,7 +128,12 @@ void v4l2_async_debug_init(struct dentry *debugfs_dir);
  * @notifier: pointer to &struct v4l2_async_notifier
  *
  * This function initializes the notifier @asd_list. It must be called
- * before the first call to @v4l2_async_notifier_add_subdev.
+ * before adding a subdevice to a notifier, using one of:
+ * @v4l2_async_notifier_add_fwnode_remote_subdev,
+ * @v4l2_async_notifier_add_fwnode_subdev,
+ * @v4l2_async_notifier_add_i2c_subdev,
+ * @v4l2_async_notifier_add_subdev or
+ * @v4l2_async_notifier_parse_fwnode_endpoints.
  */
 void v4l2_async_notifier_init(struct v4l2_async_notifier *notifier);
 

@@ -262,9 +267,11 @@ void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier);
  * sub-devices allocated for the purposes of the notifier but not the notifier
  * itself. The user is responsible for calling this function to clean up the
  * notifier after calling
- * @v4l2_async_notifier_add_subdev,
- * @v4l2_async_notifier_parse_fwnode_endpoints or
- * @v4l2_async_register_subdev_sensor_common.
+ * @v4l2_async_notifier_add_fwnode_remote_subdev,
+ * @v4l2_async_notifier_add_fwnode_subdev,
+ * @v4l2_async_notifier_add_i2c_subdev,
+ * @v4l2_async_notifier_add_subdev or
+ * @v4l2_async_notifier_parse_fwnode_endpoints.
  *
  * There is no harm from calling v4l2_async_notifier_cleanup in other
  * cases as long as its memory has been zeroed after it has been