On 1/28/21 9:09 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.
>
> Document functions that drivers should use, and their purpose.
>
> 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 | 41 ++++++++++++++++---
> include/media/v4l2-async.h | 15 +++++--
> 2 files changed, 47 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
> index 0e82c77cf3e2..a6b82b9c8210 100644
> --- a/Documentation/driver-api/media/v4l2-subdev.rst
> +++ b/Documentation/driver-api/media/v4l2-subdev.rst
> @@ -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.
If I understand correctly, these functions are for bridge and ISP drivers to tell
the framework they are waiting asynchronously for another sub-device.
I wonder if this could be re-phrased a bit to convey that.
Shouldn't __v4l2_async_notifier_add_subdev() and v4l2_async_notifier_parse_fwnode_endpoints()
also be mentioned here?
Or maybe just don't mention __v4l2_async_notifier_add_subdev() here to discourage its usage.
I see that v4l2_async_notifier_parse_fwnode_endpoints() is only used by sun6i_csi.c,
I wonder if sun6i is a special case of if we could use one of those 3 functions instead
and discourage the usage of v4l2_async_notifier_parse_fwnode_endpoints() as well.
> +
> +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(¬ifier, 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()``
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index b94f0a0a8042..6dac6cb6290f 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_remote_subdev,
> + * @v4l2_async_notifier_add_fwnode_subdev,
> + * @v4l2_async_notifier_add_i2c_subdev,
> + * @v4l2_async_notifier_add_subdev or
v4l2_async_notifier_add_subdev() was renamed on patch 12/14.
Maybe just don't mention it here to discourage its usage?
> + * @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
Same here.
Thanks
Helen
> + * @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
>
