driver-api/media/camera-sensor.rst

1 .. SPDX-License-Identifier: GPL-2.0
3 Writing camera sensor drivers
6 CSI-2 and parallel (BT.601 and BT.656) busses
7 ---------------------------------------------
9 Please see :ref:`transmitter-receiver`.
12 ---------------
23 elsewhere. Therefore only the pre-determined frequencies are configurable by the
29 Read the ``clock-frequency`` _DSD property to denote the frequency. The driver
35 The currently preferred way to achieve this is using ``assigned-clocks``,
36 ``assigned-clock-parents`` and ``assigned-clock-rates`` properties. See
37 ``Documentation/devicetree/bindings/clock/clock-bindings.txt`` for more
46 ----------
51 Freely configurable camera sensor drivers
54 Freely configurable camera sensor drivers expose the device's internal
55 processing pipeline as one or more sub-devices with different cropping and
70 Most sensor drivers are implemented this way, see e.g.
74 ----------------------------
84 a result of the configuration of a number of camera sensor implementation
100 the sensor's **pixel array** is specified by ``V4L2_CID_PIXEL_RATE`` in the same
101 sub-device. The unit of that control is pixels per second.
103 Register list based drivers need to implement read-only sub-device nodes for the
109 skipping, scaling or digital crop :ref:`v4l2-subdev-selections`.
120 Power management
121 ----------------
123 Always use runtime PM to manage the power states of your device. Camera sensor
125 controlling the power state of the device they otherwise control as well. In
129 Existing camera sensor drivers may rely on the old
130 struct v4l2_subdev_core_ops->s_power() callback for bridge or ISP drivers to
131 manage their power state. This is however **deprecated**. If you feel you need
133 runtime PM support to the sensor driver you are using. Likewise, new drivers
137 ``drivers/media/i2c/ccs/ccs-core.c``. The two drivers work in both ACPI
144 PM ``runtime_resume`` callback, as it has no way to figure out the power state
145 of the device. This is because the power state of the device is only changed
146 after the power state transition has taken place. The ``s_ctrl`` callback can be
147 used to obtain device's power state after the power state transition:
151 The function returns a non-zero value if it succeeded getting the power count or
156 ----------------------------------
158 Some systems have the camera sensor mounted upside down compared to its natural
161 <v4l2-camera-sensor-rotation>` control.
163 Sensor drivers shall also report the sensor's mounting orientation with the
164 :ref:`V4L2_CID_CAMERA_SENSOR_ORIENTATION <v4l2-camera-sensor-orientation>`.
170 Sensor drivers that have any vertical or horizontal flips embedded in the
174 controls shall not be inverted, independently of the sensor's mounting