openwrt/target/linux/bcm27xx/patches-6.6/950-1150-media-uapi-Document-meta-pixel-format-for-PiSP-BE-co.patch

From 7ca73020a5b26599d539083e413784e79891107e Mon Sep 17 00:00:00 2001
From: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Date: Fri, 26 Jan 2024 15:04:59 +0100
Subject: [PATCH 1150/1215] media: uapi: Document meta pixel format for PiSP BE
 config

Add format description for the PiSP Back End configuration parameter
buffer.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
---
 .../userspace-api/media/v4l/meta-formats.rst  |  1 +
 .../media/v4l/metafmt-pisp-be.rst             | 56 +++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst

--- a/Documentation/userspace-api/media/v4l/meta-formats.rst
+++ b/Documentation/userspace-api/media/v4l/meta-formats.rst
@@ -15,6 +15,7 @@ These formats are used for the :ref:`met
     metafmt-bcm2835-isp-stats
     metafmt-d4xx
     metafmt-intel-ipu3
+    metafmt-pisp-be
     metafmt-rkisp1
     metafmt-sensor-data
     metafmt-uvc
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
@@ -0,0 +1,56 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _v4l2-meta-fmt-rpi-be-cfg:
+
+************************
+V4L2_META_FMT_RPI_BE_CFG
+************************
+
+Raspberry Pi PiSP Back End configuration format
+===============================================
+
+The Raspberry Pi PiSP Back End memory-to-memory image signal processor is
+configured by userspace by providing a buffer of configuration parameters
+to the `pispbe-config` output video device node using the
+:c:type:`v4l2_meta_format` interface.
+
+The PiSP Back End processes images in tiles, and its configuration requires
+specifying two different sets of parameters by populating the members of
+:c:type:`pisp_be_tiles_config` defined in the ``pisp_be_config.h`` header file.
+
+The `Raspberry Pi PiSP technical specification
+<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>`_
+provide detailed description of the ISP back end configuration and programming
+model.
+
+Global configuration data
+-------------------------
+
+The global configuration data describe how the pixels in a particular image are
+to be processed and is therefore shared across all the tiles of the image. So
+for example, LSC (Lens Shading Correction) or Denoise parameters would be common
+across all tiles from the same frame.
+
+Global configuration data are passed to the ISP by populating the member of
+:c:type:`pisp_be_config`.
+
+Tile parameters
+---------------
+
+As the ISP processes images in tiles, each set of tiles parameters describe how
+a single tile in an image is going to be processed. A single set of tile
+parameters consist of 160 bytes of data and to process a batch of tiles several
+sets of tiles parameters are required.
+
+Tiles parameters are passed to the ISP by populating the member of
+``pisp_tile`` and the ``num_tiles`` fields of :c:type:`pisp_be_tiles_config`.
+
+Raspberry Pi PiSP Back End uAPI data types
+==========================================
+
+This section describes the data types exposed to userspace by the Raspberry Pi
+PiSP Back End. The section is informative only, for a detailed description of
+each field refer to the `Raspberry Pi PiSP technical specification
+<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>`_.
+
+.. kernel-doc:: include/uapi/linux/media/raspberrypi/pisp_be_config.h