[PATCH v4 7/7] media: open.rst: add a notice about subdev-API on vdev-centric

[Mauro Carvalho Chehab]

The documentation doesn't mention if vdev-centric hardware
control would have subdev API or not.

Add a notice about that, reflecting the current status, where
three drivers use it, in order to support some subdev-specific
controls.

Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
---
 Documentation/media/uapi/v4l/open.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/media/uapi/v4l/open.rst b/Documentation/media/uapi/v4l/open.rst
index d0930fc170f0..48f628bbabc7 100644
--- a/Documentation/media/uapi/v4l/open.rst
+++ b/Documentation/media/uapi/v4l/open.rst
@@ -46,6 +46,13 @@ the periferal can be used. For such devices, the sub-devices' configuration
 can be controlled via the :ref:`sub-device API <subdev>`, which creates one
 device node per sub-device.
 
+.. note::
+
+   A **vdev-centric** may also optionally expose V4L2 sub-devices via
+   :ref:`sub-device API <subdev>`. In that case, it has to implement
+   the :ref:`media controller API <media_controller>` as well.
+
+
 .. attention::
 
    Devices that require **mc-centric** hardware peripheral control should
-- 
2.13.3