Add user documentation for the CCS driver. This includes e.g. sub-devices implemented by the driver. Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> --- .../userspace-api/media/drivers/ccs.rst | 59 +++++++++++++++++++ .../userspace-api/media/drivers/index.rst | 1 + MAINTAINERS | 1 + 3 files changed, 61 insertions(+) create mode 100644 Documentation/userspace-api/media/drivers/ccs.rst diff --git a/Documentation/userspace-api/media/drivers/ccs.rst b/Documentation/userspace-api/media/drivers/ccs.rst new file mode 100644 index 000000000000..9f507b0a79b5 --- /dev/null +++ b/Documentation/userspace-api/media/drivers/ccs.rst @@ -0,0 +1,59 @@ +.. SPDX-License-Identifier: GPL-2.0-only OR BSD-3-Clause + +.. include:: <isonum.txt> + +MIPI CCS camera sensor driver +============================= + +The MIPI CCS camera sensor driver is a generic driver for `MIPI CCS +<https://www.mipi.org/specifications/camera-command-set>`_ compliant +camera sensors. It exposes three sub-devices representing the pixel array, +the binner and the scaler. + +As the capabilities of individual devices vary, the driver exposes +interfaces based on the capabilities that exist in hardware. + +Pixel Array sub-device +---------------------- + +The pixel array sub-device represents the camera sensor's pixel matrix, as well +as analogue crop functionality present in many compliant devices. The analogue +crop is configured using the ``V4L2_SEL_TGT_CROP`` on the source pad (0) of the +entity. The size of the pixel matrix can be obtained by getting the +``V4L2_SEL_TGT_NATIVE_SIZE`` target. + +Binner +------ + +The binner sub-device represents the binning functionality on the sensor. For +that purpose, selection target ``V4L2_SEL_TGT_COMPOSE`` is supported on the +sink pad (0). + +Additionally, if a device has no scaler or digital crop functionality, the +source pad (1) expses another digital crop selection rectangle that can only +crop at the end of the lines and frames. + +Scaler +------ + +The scaler sub-device represents the digital crop and scaling functionality of +the sensor. The V4L2 selection target ``V4L2_SEL_TGT_CROP`` is used to +configure the digital crop on the sink pad (0) when digital crop is supported. +Scaling is configured using selection target ``V4L2_SEL_TGT_COMPOSE`` on the +sink pad (0) as well. + +Additionally, if the scaler sub-device exists, its source pad (1) exposes +another digital crop selection rectangle that can only crop at the end of the +lines and frames. + +Digital and analogue crop +------------------------- + +Digital crop functionality is referred to as cropping that effectively works by +dropping some data on the floor. Analogue crop, on the other hand, means that +the cropped information is never retrieved. In case of camera sensors, the +analogue data is never read from the pixel matrix that are outside the +configured selection rectangle that designates crop. The difference has an +effect in device timing and likely also in power consumption. + +**Copyright** |copy| 2020 Intel Corporation diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst index 05a82f8c0c99..1a9038f5f9fa 100644 --- a/Documentation/userspace-api/media/drivers/index.rst +++ b/Documentation/userspace-api/media/drivers/index.rst @@ -31,6 +31,7 @@ For more details see the file COPYING in the source distribution of Linux. :maxdepth: 5 :numbered: + ccs cx2341x-uapi imx-uapi max2175 diff --git a/MAINTAINERS b/MAINTAINERS index e97d4d9d741e..ab0bf9b8dd72 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -11644,6 +11644,7 @@ L: linux-media@xxxxxxxxxxxxxxx S: Maintained F: Documentation/devicetree/bindings/media/i2c/mipi-ccs.yaml F: Documentation/driver-api/media/drivers/ccs/ +F: Documentation/userspace-api/media/drivers/ccs.rst F: drivers/media/i2c/ccs-pll.c F: drivers/media/i2c/ccs-pll.h F: drivers/media/i2c/ccs/ -- 2.29.2
