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[RESEND,v5,1/1] Documentation: v4l: Document rotation and orientation for sensor drivers

Message ID 20230406125340.3282872-1-sakari.ailus@linux.intel.com
State Superseded
Headers show
Series [RESEND,v5,1/1] Documentation: v4l: Document rotation and orientation for sensor drivers | expand

Commit Message

Sakari Ailus April 6, 2023, 12:53 p.m. UTC 
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>
---
since v4:

- Add "flipping" to the section name.

- Add a note on flipping controls not being inverted.

- Move the flipping related paragraph to the end of the section.

 .../driver-api/media/camera-sensor.rst        | 22 +++++++++++++++++++
 .../media/v4l/ext-ctrls-camera.rst            |  3 +++
 2 files changed, 25 insertions(+)
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Patch

diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst
index c7d4891bd24e7..93f4f2536c250 100644
--- a/Documentation/driver-api/media/camera-sensor.rst
+++ b/Documentation/driver-api/media/camera-sensor.rst
@@ -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.
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
index daa4f40869f8f..cdc515c604683 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
@@ -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