c3-isp.rst

  1.. SPDX-License-Identifier: (GPL-2.0-only OR MIT)
  2
  3.. include:: <isonum.txt>
  4
  5=================================================
  6Amlogic C3 Image Signal Processing (C3ISP) driver
  7=================================================
  8
  9Introduction
 10============
 11
 12This file documents the Amlogic C3ISP driver located under
 13drivers/media/platform/amlogic/c3/isp.
 14
 15The current version of the driver supports the C3ISP found on
 16Amlogic C308L processor.
 17
 18The driver implements V4L2, Media controller and V4L2 subdev interfaces.
 19Camera sensor using V4L2 subdev interface in the kernel is supported.
 20
 21The driver has been tested on AW419-C308L-Socket platform.
 22
 23Amlogic C3 ISP
 24==============
 25
 26The Camera hardware found on C308L processors and supported by
 27the driver consists of:
 28
 29- 1 MIPI-CSI-2 module: handles the physical layer of the MIPI CSI-2 receiver and
 30  receives data from the connected camera sensor.
 31- 1 MIPI-ADAPTER module: organizes MIPI data to meet ISP input requirements and
 32  send MIPI data to ISP.
 33- 1 ISP (Image Signal Processing) module: contains a pipeline of image processing
 34  hardware blocks. The ISP pipeline contains three resizers at the end each of
 35  them connected to a DMA interface which writes the output data to memory.
 36
 37A high-level functional view of the C3 ISP is presented below.::
 38
 39                                                                   +----------+    +-------+
 40                                                                   | Resizer  |--->| WRMIF |
 41  +---------+    +------------+    +--------------+    +-------+   |----------+    +-------+
 42  | Sensor  |--->| MIPI CSI-2 |--->| MIPI ADAPTER |--->|  ISP  |---|----------+    +-------+
 43  +---------+    +------------+    +--------------+    +-------+   | Resizer  |--->| WRMIF |
 44                                                                   +----------+    +-------+
 45                                                                   |----------+    +-------+
 46                                                                   | Resizer  |--->| WRMIF |
 47                                                                   +----------+    +-------+
 48
 49Driver architecture and design
 50==============================
 51
 52With the goal to model the hardware links between the modules and to expose a
 53clean, logical and usable interface, the driver registers the following V4L2
 54sub-devices:
 55
 56- 1 `c3-mipi-csi2` sub-device - the MIPI CSI-2 receiver
 57- 1 `c3-mipi-adapter` sub-device - the MIPI adapter
 58- 1 `c3-isp-core` sub-device - the ISP core
 59- 3 `c3-isp-resizer` sub-devices - the ISP resizers
 60
 61The `c3-isp-core` sub-device is linked to 2 video device nodes for statistics
 62capture and parameters programming:
 63
 64- the `c3-isp-stats` capture video device node for statistics capture
 65- the `c3-isp-params` output video device for parameters programming
 66
 67Each `c3-isp-resizer` sub-device is linked to a capture video device node where
 68frames are captured from:
 69
 70- `c3-isp-resizer0` is linked to the `c3-isp-cap0` capture video device
 71- `c3-isp-resizer1` is linked to the `c3-isp-cap1` capture video device
 72- `c3-isp-resizer2` is linked to the `c3-isp-cap2` capture video device
 73
 74The media controller pipeline graph is as follows (with connected a
 75IMX290 camera sensor):
 76
 77.. _isp_topology_graph:
 78
 79.. kernel-figure:: c3-isp.dot
 80    :alt:   c3-isp.dot
 81    :align: center
 82
 83    Media pipeline topology
 84
 85Implementation
 86==============
 87
 88Runtime configuration of the ISP hardware is performed on the `c3-isp-params`
 89video device node using the :ref:`V4L2_META_FMT_C3ISP_PARAMS
 90<v4l2-meta-fmt-c3isp-params>` as data format. The buffer structure is defined by
 91:c:type:`c3_isp_params_cfg`.
 92
 93Statistics are captured from the `c3-isp-stats` video device node using the
 94:ref:`V4L2_META_FMT_C3ISP_STATS <v4l2-meta-fmt-c3isp-stats>` data format.
 95
 96The final picture size and format is configured using the V4L2 video
 97capture interface on the `c3-isp-cap[0, 2]` video device nodes.
 98
 99The Amlogic C3 ISP is supported by `libcamera <https://libcamera.org>`_ with a
100dedicated pipeline handler and algorithms that perform run-time image correction
101and enhancement.