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Add the file 'c3-isp.rst' that documents the c3-isp driver. Signed-off-by: Keke Li <keke.li@amlogic.com> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
101 lines
4 KiB
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101 lines
4 KiB
ReStructuredText
.. SPDX-License-Identifier: (GPL-2.0-only OR MIT)
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.. include:: <isonum.txt>
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=================================================
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Amlogic C3 Image Signal Processing (C3ISP) driver
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=================================================
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Introduction
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============
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This file documents the Amlogic C3ISP driver located under
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drivers/media/platform/amlogic/c3/isp.
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The current version of the driver supports the C3ISP found on
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Amlogic C308L processor.
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The driver implements V4L2, Media controller and V4L2 subdev interfaces.
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Camera sensor using V4L2 subdev interface in the kernel is supported.
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The driver has been tested on AW419-C308L-Socket platform.
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Amlogic C3 ISP
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==============
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The Camera hardware found on C308L processors and supported by
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the driver consists of:
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- 1 MIPI-CSI-2 module: handles the physical layer of the MIPI CSI-2 receiver and
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receives data from the connected camera sensor.
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- 1 MIPI-ADAPTER module: organizes MIPI data to meet ISP input requirements and
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send MIPI data to ISP.
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- 1 ISP (Image Signal Processing) module: contains a pipeline of image processing
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hardware blocks. The ISP pipeline contains three resizers at the end each of
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them connected to a DMA interface which writes the output data to memory.
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A high-level functional view of the C3 ISP is presented below.::
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+----------+ +-------+
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| Resizer |--->| WRMIF |
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+---------+ +------------+ +--------------+ +-------+ |----------+ +-------+
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| Sensor |--->| MIPI CSI-2 |--->| MIPI ADAPTER |--->| ISP |---|----------+ +-------+
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+---------+ +------------+ +--------------+ +-------+ | Resizer |--->| WRMIF |
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+----------+ +-------+
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|----------+ +-------+
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| Resizer |--->| WRMIF |
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+----------+ +-------+
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Driver architecture and design
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==============================
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With the goal to model the hardware links between the modules and to expose a
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clean, logical and usable interface, the driver registers the following V4L2
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sub-devices:
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- 1 `c3-mipi-csi2` sub-device - the MIPI CSI-2 receiver
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- 1 `c3-mipi-adapter` sub-device - the MIPI adapter
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- 1 `c3-isp-core` sub-device - the ISP core
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- 3 `c3-isp-resizer` sub-devices - the ISP resizers
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The `c3-isp-core` sub-device is linked to 2 video device nodes for statistics
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capture and parameters programming:
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- the `c3-isp-stats` capture video device node for statistics capture
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- the `c3-isp-params` output video device for parameters programming
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Each `c3-isp-resizer` sub-device is linked to a capture video device node where
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frames are captured from:
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- `c3-isp-resizer0` is linked to the `c3-isp-cap0` capture video device
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- `c3-isp-resizer1` is linked to the `c3-isp-cap1` capture video device
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- `c3-isp-resizer2` is linked to the `c3-isp-cap2` capture video device
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The media controller pipeline graph is as follows (with connected a
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IMX290 camera sensor):
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.. _isp_topology_graph:
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.. kernel-figure:: c3-isp.dot
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:alt: c3-isp.dot
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:align: center
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Media pipeline topology
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Implementation
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==============
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Runtime configuration of the ISP hardware is performed on the `c3-isp-params`
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video device node using the :ref:`V4L2_META_FMT_C3ISP_PARAMS
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<v4l2-meta-fmt-c3isp-params>` as data format. The buffer structure is defined by
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:c:type:`c3_isp_params_cfg`.
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Statistics are captured from the `c3-isp-stats` video device node using the
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:ref:`V4L2_META_FMT_C3ISP_STATS <v4l2-meta-fmt-c3isp-stats>` data format.
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The final picture size and format is configured using the V4L2 video
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capture interface on the `c3-isp-cap[0, 2]` video device nodes.
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The Amlogic C3 ISP is supported by `libcamera <https://libcamera.org>`_ with a
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dedicated pipeline handler and algorithms that perform run-time image correction
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and enhancement.
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