Document how embedded data support should be implemented for camera sensors, and when and how CCS embedded data format should be referenced. Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> --- .../media/drivers/camera-sensor.rst | 28 +++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/Documentation/userspace-api/media/drivers/camera-sensor.rst b/Documentation/userspace-api/media/drivers/camera-sensor.rst index 919a50e8b9d9..308f391c5ca1 100644 --- a/Documentation/userspace-api/media/drivers/camera-sensor.rst +++ b/Documentation/userspace-api/media/drivers/camera-sensor.rst @@ -102,3 +102,31 @@ register programming sequences shall initialize the :ref:`V4L2_CID_HFLIP 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. + +Embedded data +------------- + +Many sensors, mostly raw sensors, support embedded data which is used to convey +the sensor configuration for the captured frame back to the host. While CSI-2 is +the most common bus used by such sensors, embedded data is not entirely limited +to CSI-2 bus due to e.g. bridge devices. + +Embedded data support should use an internal source pad and route to the +external pad. If embedded data output can be disabled in hardware, it should be +possible to disable the embedded data route via ``VIDIOC_SUBDEV_S_ROUTING`` +IOCTL. + +In general, changing the embedded data format from the driver-configured values +is not supported. The height of the metadata is hardware specific and the width +is that (or less of that) of the image width, as configured on the pixel data +stream. + +CCS and non-CCS embedded data +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Embedded data which is compliant with CCS definitions shall use ``CCS embedded +data format <MEDIA-BUS-FMT-CCS-EMBEDDED>``. Device specific embedded data which +is compliant up to MIPI CCS embedded data levels 1 or 2 only shall refer to CCS +embedded data formats and document the level of conformance. The rest of the +device specific embedded data format shall be documented in the context of the +data format itself. -- 2.39.2
