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Diffstat (limited to 'Documentation/driver-api/media/v4l2-subdev.rst')
| -rw-r--r-- | Documentation/driver-api/media/v4l2-subdev.rst | 48 |
1 files changed, 39 insertions, 9 deletions
diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst index 0e82c77cf3e2..8b53da2f9c74 100644 --- a/Documentation/driver-api/media/v4l2-subdev.rst +++ b/Documentation/driver-api/media/v4l2-subdev.rst @@ -197,15 +197,45 @@ unregister the notifier the driver has to call takes two arguments: a pointer to struct :c:type:`v4l2_device` and a pointer to struct :c:type:`v4l2_async_notifier`. -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`. +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. 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_notifier_add_fwnode_remote_subdev` and +:c:func:`v4l2_async_notifier_add_i2c_subdev` are for bridge and ISP drivers for +registering their async sub-devices with the notifier. + +:c:func:`v4l2_async_register_subdev_sensor_common` is a helper function for +sensor drivers registering their own async sub-device, but it also registers a +notifier and further registers async sub-devices for lens and flash devices +found in firmware. The notifier for the sub-device is unregistered with the +async sub-device. + +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()`` |