media: Documentation: Initialisation finishes before subdev registration

[linux-2.6-microblaze.git] / Documentation / driver-api / media / v4l2-subdev.rst

diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
index a62e4af..1db2ba2 100644 (file)
--- a/Documentation/driver-api/media/v4l2-subdev.rst
+++ b/Documentation/driver-api/media/v4l2-subdev.rst
@@ -181,6 +181,8 @@ You can unregister a sub-device using:
 Afterwards the subdev module can be unloaded and
 :c:type:`sd <v4l2_subdev>`->dev == ``NULL``.
 
+.. _media-registering-async-subdevs:
+
 Registering asynchronous sub-devices
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -195,6 +197,11 @@ performed using the :c:func:`v4l2_async_unregister_subdev` call. Subdevices
 registered this way are stored in a global list of subdevices, ready to be
 picked up by bridge drivers.
 
+Drivers must complete all initialization of the sub-device before
+registering it using :c:func:`v4l2_async_register_subdev`, including
+enabling runtime PM. This is because the sub-device becomes accessible
+as soon as it gets registered.
+
 Asynchronous sub-device notifiers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^