On 03/10/2023 13:52, Sakari Ailus wrote: > 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 "internal source pad" -> "internal sink pad"? > +external pad. If embedded data output can be disabled in hardware, it should be "external pad" -> "external source pad"? Or perhaps "a source pad of the entity"? Regards, Hans > +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.
