driver-api/media/camera-sensor.rst

1 .. SPDX-License-Identifier: GPL-2.0
5 Writing camera sensor drivers
8 This document covers the in-kernel APIs only. For the best practices on
9 userspace API implementation in camera sensor drivers, please see
12 CSI-2, parallel and BT.656 buses
13 --------------------------------
15 Please see :ref:`transmitter-receiver`.
18 ---------------
29 elsewhere. Therefore only the pre-determined frequencies are configurable by the
35 Read the ``clock-frequency`` _DSD property to denote the frequency. The driver
41 The preferred way to achieve this is using ``assigned-clocks``,
42 ``assigned-clock-parents`` and ``assigned-clock-rates`` properties. See the
44 <https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml>`_
53 Power management
54 ----------------
57 pipeline. They must obey the rules listed herein to ensure coherent power
60 Camera sensor drivers are responsible for controlling the power state of the
62 power states. Runtime PM shall be enabled at probe time and disabled at remove
64 :ref:`async sub-device registration <media-registering-async-subdevs>`.
67 system resources required to power the sensor up and down. For drivers that
75 streaming. They may power the device up at probe time (for example to read
81 camera sensor and the rest of the camera pipeline. Bridge drivers are
85 sensor drivers shall therefore **not** keep track of the streaming state to
89 Camera sensor drivers shall **not** implement the subdev ``.s_power()``
93 a bridge driver, instead add runtime PM support to the sensor driver you are
96 Please also see :ref:`examples <media-camera-sensor-examples>`.
102 PM ``runtime_resume`` callback, as it has no way to figure out the power state
103 of the device. This is because the power state of the device is only changed
104 after the power state transition has taken place. The ``s_ctrl`` callback can be
105 used to obtain device's power state after the power state transition:
109 The function returns a non-zero value if it succeeded getting the power count or
114 ----------------------------------
120 .. _media-camera-sensor-examples:
123 ---------------
125 Features implemented by sensor drivers vary, and depending on the set of
126 supported features and other qualities, particular sensor drivers better serve
129 .. flat-table:: Example sensor drivers
130     :header-rows: 0
133     * - Driver name
134       - File(s)
135       - Driver type
136       - Example topic
137     * - CCS
138       - ``drivers/media/i2c/ccs/``
139       - Freely configurable
140       - Power management (ACPI and DT), UAPI
141     * - imx219
142       - ``drivers/media/i2c/imx219.c``
143       - Register list based
144       - Power management (DT), UAPI, mode selection
145     * - imx319
146       - ``drivers/media/i2c/imx319.c``
147       - Register list based
148       - Power management (ACPI and DT)