On 1/25/21 10:22 AM, Sakari Ailus wrote:
> From: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
>
> Now that most users of v4l2_async_notifier_add_subdev have
> been converted, let's fix the documentation so it's more clear
> how the v4l2-async API should be used.
>
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
> .../driver-api/media/v4l2-subdev.rst | 38 ++++++++++++++++---
> include/media/v4l2-async.h | 15 ++++++--
> 2 files changed, 44 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
> index 0e82c77cf3e2..490dd212345d 100644
> --- a/Documentation/driver-api/media/v4l2-subdev.rst
> +++ b/Documentation/driver-api/media/v4l2-subdev.rst
> @@ -201,11 +201,39 @@ 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:
> +:c:func:`v4l2_async_notifier_add_fwnode_subdev`,
> +:c:func:`v4l2_async_notifier_add_fwnode_remote_subdev` or
> +:c:func:`v4l2_async_notifier_add_i2c_subdev`.
> +
> +These functions allocate a subdevice descriptor, which is of
> +type struct :c:type:`v4l2_async_subdev`, and take a size argument
> +which can be used to embed the descriptor in a driver-specific
> +async subdevice 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 v4l2_async_subdev *asd;
> + struct fwnode_handle *ep;
> +
> + ...
> +
> + asd = v4l2_async_notifier_add_fwnode_subdev(
> + ¬ifier, ep, sizeof(*my_asd));
> + fwnode_handle_put(ep);
> +
> + if (IS_ERR(asd))
> + return PTR_ERR(asd);
> +
> + my_asd = container_of(asd, struct my_async_subdev, asd);
>
> The V4L2 core will then use these descriptors to match asynchronously
> registered subdevices to them. If a match is detected the ``.bound()``
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index f2cac0931372..25c9ebd3f963 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -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_subdev,
> + * @v4l2_async_register_subdev_sensor_common,
This function doesn't receive a notifier, it is used by the sensor at probe's
time to inform the framework this sensor is present (if I understand correctly).
So it could be called before the isp (who is registering a notifier) is probed.
There is no need to call v4l2_async_notifier_init() before
v4l2_async_register_subdev_sensor_common() in my understanding.
> + * @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);
>
> @@ -248,9 +253,11 @@ 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_subdev,
> + * @v4l2_async_register_subdev_sensor_common,
The user of v4l2_async_register_*() is not responsible
for cleaning up the notifier with v4l2_async_notifier_unregister(),
it calls v4l2_async_unregister_*() instead
(or am I missing something?)
Thanks
Helen
> + * @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
>
