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[v4,09/23] media: Documentation: Document embedded data guidelines for camera sensors

Message ID 20230922142239.259425-10-sakari.ailus@linux.intel.com
State New
Headers show
Series Generic line based metadata support, internal pads | expand

Commit Message

Sakari Ailus Sept. 22, 2023, 2:22 p.m. UTC
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@linux.intel.com>
---
 .../driver-api/media/camera-sensor.rst        | 23 +++++++++++++++++++
 1 file changed, 23 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 2acc08142a1a..64c74fa51586 100644
--- a/Documentation/driver-api/media/camera-sensor.rst
+++ b/Documentation/driver-api/media/camera-sensor.rst
@@ -200,3 +200,26 @@  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.
+
+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.
+
+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.