[PATCH v2 12/14] media: Clarify v4l2-async subdevice addition API
From: Ezequiel Garcia <hidden>
Date: 2021-01-17 18:34:00
Subsystem:
media input infrastructure (v4l/dvb), the rest, v4l2 async and fwnode frameworks · Maintainers:
Mauro Carvalho Chehab, Linus Torvalds, Sakari Ailus
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 <redacted> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- .../driver-api/media/v4l2-subdev.rst | 38 ++++++++++++++++--- include/media/v4l2-async.h | 11 ++++-- 2 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
index bb5b1a7cdfd9..47a70538d758 100644
--- a/Documentation/driver-api/media/v4l2-subdev.rst
+++ b/Documentation/driver-api/media/v4l2-subdev.rst@@ -204,11 +204,39 @@ 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 d2af7a5aef4c..3622ea938360 100644
--- a/include/media/v4l2-async.h
+++ b/include/media/v4l2-async.h@@ -128,7 +128,11 @@ 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_i2c_subdev, + * @v4l2_async_notifier_add_fwnode_subdev, + * @v4l2_async_notifier_add_fwnode_remote_subdev or + * @v4l2_async_notifier_parse_fwnode_sensor_common. */ void v4l2_async_notifier_init(struct v4l2_async_notifier *notifier);
@@ -248,8 +252,9 @@ 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_notifier_add_i2c_subdev, + * @v4l2_async_notifier_add_fwnode_subdev, + * @v4l2_async_notifier_add_fwnode_remote_subdev or * @v4l2_async_notifier_parse_fwnode_sensor_common. * * There is no harm from calling v4l2_async_notifier_cleanup in other
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2.29.2