1.. SPDX-License-Identifier: GPL-2.0 2.. c:namespace:: V4L 3 4.. _v4l2-meta-fmt-rpi-be-cfg: 5 6************************ 7V4L2_META_FMT_RPI_BE_CFG 8************************ 9 10Raspberry Pi PiSP Back End configuration format 11=============================================== 12 13The Raspberry Pi PiSP Back End memory-to-memory image signal processor is 14configured by userspace by providing a buffer of configuration parameters 15to the `pispbe-config` output video device node using the 16:c:type:`v4l2_meta_format` interface. 17 18The PiSP Back End processes images in tiles, and its configuration requires 19specifying two different sets of parameters by populating the members of 20:c:type:`pisp_be_tiles_config` defined in the ``pisp_be_config.h`` header file. 21 22The `Raspberry Pi PiSP technical specification 23<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>`_ 24provide detailed description of the ISP back end configuration and programming 25model. 26 27Global configuration data 28------------------------- 29 30The global configuration data describe how the pixels in a particular image are 31to be processed and is therefore shared across all the tiles of the image. So 32for example, LSC (Lens Shading Correction) or Denoise parameters would be common 33across all tiles from the same frame. 34 35Global configuration data are passed to the ISP by populating the member of 36:c:type:`pisp_be_config`. 37 38Tile parameters 39--------------- 40 41As the ISP processes images in tiles, each set of tiles parameters describe how 42a single tile in an image is going to be processed. A single set of tile 43parameters consist of 160 bytes of data and to process a batch of tiles several 44sets of tiles parameters are required. 45 46Tiles parameters are passed to the ISP by populating the member of 47``pisp_tile`` and the ``num_tiles`` fields of :c:type:`pisp_be_tiles_config`. 48 49Raspberry Pi PiSP Back End uAPI data types 50========================================== 51 52This section describes the data types exposed to userspace by the Raspberry Pi 53PiSP Back End. The section is informative only, for a detailed description of 54each field refer to the `Raspberry Pi PiSP technical specification 55<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>`_. 56 57.. kernel-doc:: include/uapi/linux/media/raspberrypi/pisp_be_config.h 58