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Documentation: v4l: Document rotation and orientation for sensor drivers

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Document how rotation and orientation should be taken into account in
writing camera sensor drivers.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
This commit is contained in:
Sakari Ailus 2023-03-28 15:54:59 +03:00 committed by Hans Verkuil
parent a73206f33b
commit 71511a24ee
2 changed files with 25 additions and 0 deletions
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22
Documentation/driver-api/media/camera-sensor.rst
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@ -151,3 +151,25 @@ used to obtain device's power state after the power state transition:
The function returns a non-zero value if it succeeded getting the power count or
runtime PM was disabled, in either of which cases the driver may proceed to
access the device.
Rotation, orientation and flipping
----------------------------------
Some systems have the camera sensor mounted upside down compared to its natural
mounting rotation. In such cases, drivers shall expose the information to
userspace with the :ref:`V4L2_CID_CAMERA_SENSOR_ROTATION
<v4l2-camera-sensor-rotation>` control.
Sensor drivers shall also report the sensor's mounting orientation with the
:ref:`V4L2_CID_CAMERA_SENSOR_ORIENTATION <v4l2-camera-sensor-orientation>`.
Use ``v4l2_fwnode_device_parse()`` to obtain rotation and orientation
information from system firmware and ``v4l2_ctrl_new_fwnode_properties()`` to
register the appropriate controls.
Sensor drivers that have any vertical or horizontal flips embedded in the
register programming sequences shall initialize the V4L2_CID_HFLIP and
V4L2_CID_VFLIP controls with the values programmed by the register sequences.
The default values of these controls shall be 0 (disabled). Especially these
controls shall not be inverted, independently of the sensor's mounting
rotation.

3
Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
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@ -506,6 +506,8 @@ enum v4l2_scene_mode -
value down. A value of zero stops the motion if one is in progress
and has no effect otherwise.
.. _v4l2-camera-sensor-orientation:
``V4L2_CID_CAMERA_ORIENTATION (menu)``
This read-only control describes the camera orientation by reporting its
mounting position on the device where the camera is installed. The control
@ -536,6 +538,7 @@ enum v4l2_scene_mode -
- The camera is not directly attached to the device and is freely movable.
.. _v4l2-camera-sensor-rotation:
``V4L2_CID_CAMERA_SENSOR_ROTATION (integer)``
This read-only control describes the rotation correction in degrees in the