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 ---------------
14 Camera sensors have an internal clock tree including a PLL and a number of
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 ----------
48 There are two distinct ways to configure the frame size produced by camera
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 ----------------------------
80 Raw camera sensors
84 a result of the configuration of a number of camera sensor implementation
86 less all modern raw camera sensors.
94 large variety of devices beyond camera sensors. Devices that have no analogue
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`.
121 ----------------
123 Always use runtime PM to manage the power states of your device. Camera sensor
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
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
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