driver-api/media/camera-sensor.rst

1 .. SPDX-License-Identifier: GPL-2.0
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
15 divisors. The clock tree is generally configured by the driver based on a few
16 input parameters that are specific to the hardware:: the external clock frequency
17 and the link frequency. The two parameters generally are obtained from system
20 The reason why the clock frequencies are so important is that the clock signals
21 come out of the SoC, and in many cases a specific frequency is designed to be
22 used in the system. Using another frequency may cause harmful effects
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
30 can rely on this frequency being used.
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
38 information. The driver then gets the frequency using ``clk_get_rate()``.
40 This approach has the drawback that there's no guarantee that the frequency
42 the board's clock tree to begin with. Changes to the Common Clock Framework API
46 ----------
55 processing pipeline as one or more sub-devices with different cropping and
74 ----------------------------
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 ----------------
130 struct v4l2_subdev_core_ops->s_power() callback for bridge or ISP drivers to
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 ----------------------------------
161 <v4l2-camera-sensor-rotation>` control.
164 :ref:`V4L2_CID_CAMERA_SENSOR_ORIENTATION <v4l2-camera-sensor-orientation>`.
167 information from system firmware and ``v4l2_ctrl_new_fwnode_properties()`` to