8.1.15. MIPI CCS camera sensor driver¶

The MIPI CCS camera sensor driver is a generic driver for MIPI CCS 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.

8.1.15.1. 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.

8.1.15.2. 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.

8.1.15.3. 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.

8.1.15.4. 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.

8.1.15.5. 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.

8.1.15.5.1. Usage¶

Conventionally the script is called this way to update the CCS driver definitions:

$ 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