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- .. 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.
- Register definition generator
- -----------------------------
- The ccs-regs.asc file contains MIPI CCS register definitions that are used
- to produce C source code files for definitions that can be better used by
- programs written in C language. As there are many dependencies between the
- produced files, please do not modify them manually as it's error-prone and
- in vain, but instead change the script producing them.
- Usage
- ~~~~~
- Conventionally the script is called this way to update the CCS driver
- definitions:
- .. code-block:: none
- $ Documentation/driver-api/media/drivers/ccs/mk-ccs-regs -k \
- -e drivers/media/i2c/ccs/ccs-regs.h \
- -L drivers/media/i2c/ccs/ccs-limits.h \
- -l drivers/media/i2c/ccs/ccs-limits.c \
- -c Documentation/driver-api/media/drivers/ccs/ccs-regs.asc
- CCS PLL calculator
- ==================
- The CCS PLL calculator is used to compute the PLL configuration, given sensor's
- capabilities as well as board configuration and user specified configuration. As
- the configuration space that encompasses all these configurations is vast, the
- PLL calculator isn't entirely trivial. Yet it is relatively simple to use for a
- driver.
- The PLL model implemented by the PLL calculator corresponds to MIPI CCS 1.1.
- .. kernel-doc:: drivers/media/i2c/ccs-pll.h
- **Copyright** |copy| 2020 Intel Corporation
|
