[PATCH 2/6] media: v4l2-ctrl: Document V4L2_CID_LOCATION

From: Jacopo Mondi
Date: Fri Aug 16 2019 - 10:17:25 EST

Add documentation for the V4L2_CID_LOCATION camera control. The newly
added read-only control reports the camera device mounting position.

Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
.../media/uapi/v4l/ext-ctrls-camera.rst | 34 +++++++++++++++++++
1 file changed, 34 insertions(+)

diff --git a/Documentation/media/uapi/v4l/ext-ctrls-camera.rst b/Documentation/media/uapi/v4l/ext-ctrls-camera.rst
index 51c1d5c9eb00..ecf151f3f0f4 100644
--- a/Documentation/media/uapi/v4l/ext-ctrls-camera.rst
+++ b/Documentation/media/uapi/v4l/ext-ctrls-camera.rst
@@ -510,6 +510,40 @@ enum v4l2_scene_mode -
value down. A value of zero stops the motion if one is in progress
and has no effect otherwise.

+ This read-only control describes the camera sensor location by
+ reporting its mounting position on the device where the camera is
+ installed. The control value is constant and not modifiable by software
+ and its value is retrieved from the firmware interface by parsing the
+ 'location' property. This control is particularly meaningful for
+ devices which have a well defined orientation, such as phones, laptops
+ and portable devices as the camera location is expressed as a position
+ relative to the device intended usage orientation. In example, a camera
+ sensor installed on the user-facing side of a phone, a tablet or a
+ laptop device is said to be installed in the ``V4L2_LOCATION_FRONT``
+ location while camera sensors installed on the side opposed to the
+ front one are said to be installed in the ``V4L2_LOCATION_BACK``
+ location. Camera sensors connected to the device by extension cables
+ which are freely movable regardless of the device orientation, such as
+ webcams and digital cameras, are said to be have
+ ``V4L2_LOCATION_EXTERNAL`` location.
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+ - The camera sensor is located on the front side of the device.
+ * - ``V4L2_LOCATION_BACK``
+ - The camera sensor is located on the back side of the device.
+ - The camera sensor is connected by extension cables to the device and
+ it's freely movable.
.. [#f1]
This control may be changed to a menu control in the future, if more
options are required.