[v5,38/38] media: Documentation: v4l: Document sub-device notifiers

Commit Message

Sakari Ailus July 17, 2023, 1:19 p.m. UTC

Document that sub-device notifiers are now registered using
v4l2_async_subdev_nf_init(). No documentation is changed as it seems that
sub-device notifiers were not documented apart from kernel-doc comments.

Signed-off-by: Sakari Ailus <[e-mail]>
Tested-by: Philipp Zabel <[e-mail]> # imx6qp
Tested-by: Niklas Söderlund <[e-mail]> # rcar + adv746x
Tested-by: Aishwarya Kothari <[e-mail]> # Apalis i.MX6Q with TC358743
Tested-by: Lad Prabhakar <[e-mail]> # Renesas RZ/G2L SMARC
---
 Documentation/driver-api/media/v4l2-subdev.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

Patch

diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
index eba5e4468282..e56b50b3f203 100644
--- a/Documentation/driver-api/media/v4l2-subdev.rst
+++ b/Documentation/driver-api/media/v4l2-subdev.rst
@@ -218,6 +218,17 @@  available. There may be one or more async connections to a given sub-device but
 this is not known at the time of adding the connections to the notifier. Async
 connections are bound as matching async sub-devices are found, one by one.
 
+Asynchronous sub-device notifier for sub-devices
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A driver that registers an asynchronous sub-device may also register an
+asynchronous notifier. This is called an asynchronous sub-device notifier andthe
+process is similar to that of a bridge driver apart from that the notifier is
+initialised using :c:func:`v4l2_async_subdev_nf_init` instead. A sub-device
+notifier may complete only after the V4L2 device becomes available, i.e. there's
+a path via async sub-devices and notifiers to a notifier that is not an
+asynchronous sub-device notifier.
+
 Asynchronous sub-device registration helper for camera sensor drivers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^