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Message-ID: <20250903100424.GB13448@pendragon.ideasonboard.com>
Date: Wed, 3 Sep 2025 12:04:24 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Bin Du <Bin.Du@....com>
Cc: mchehab@...nel.org, hverkuil@...all.nl, bryan.odonoghue@...aro.org,
	sakari.ailus@...ux.intel.com,
	prabhakar.mahadev-lad.rj@...renesas.com,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	sultan@...neltoast.com, pratap.nirujogi@....com,
	benjamin.chan@....com, king.li@....com, gjorgji.rosikopulos@....com,
	Phil.Jawich@....com, Dominic.Antony@....com,
	mario.limonciello@....com, richard.gong@....com, anson.tsao@....com,
	Svetoslav Stoilov <Svetoslav.Stoilov@....com>
Subject: Re: [PATCH v3 7/7] Documentation: add documentation of AMD isp 4
 driver

Hi Bin,

Thank you for the patch.

On Thu, Aug 28, 2025 at 06:08:11PM +0800, Bin Du wrote:
> Add documentation for AMD isp 4 and describe the main components
> 
> Co-developed-by: Svetoslav Stoilov <Svetoslav.Stoilov@....com>
> Signed-off-by: Svetoslav Stoilov <Svetoslav.Stoilov@....com>
> Signed-off-by: Bin Du <Bin.Du@....com>
> ---
>  Documentation/admin-guide/media/amdisp4-1.rst | 66 +++++++++++++++++++
>  Documentation/admin-guide/media/amdisp4.dot   |  8 +++
>  .../admin-guide/media/v4l-drivers.rst         |  1 +
>  MAINTAINERS                                   |  2 +
>  4 files changed, 77 insertions(+)
>  create mode 100644 Documentation/admin-guide/media/amdisp4-1.rst
>  create mode 100644 Documentation/admin-guide/media/amdisp4.dot
> 
> diff --git a/Documentation/admin-guide/media/amdisp4-1.rst b/Documentation/admin-guide/media/amdisp4-1.rst
> new file mode 100644
> index 000000000000..a5ed78912d0f
> --- /dev/null
> +++ b/Documentation/admin-guide/media/amdisp4-1.rst
> @@ -0,0 +1,66 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +.. include:: <isonum.txt>
> +
> +====================================
> +AMD Image Signal Processor (amdisp4)
> +====================================
> +
> +Introduction
> +============
> +
> +This file documents the driver for the AMD ISP4 that is part of
> +AMD Ryzen AI Max 385 SoC.
> +
> +The driver is located under drivers/media/platform/amd/isp4 and uses
> +the Media-Controller API.
> +
> +Topology
> +========
> +
> +.. _amdisp4_topology_graph:
> +
> +.. kernel-figure:: amdisp4.dot
> +     :alt:   Diagram of the media pipeline topology
> +     :align: center
> +
> +
> +
> +The driver has 1 sub-device:
> +
> +- isp: used to resize and process bayer raw frames in to yuv.
> +
> +The driver has 1 video device:
> +
> +- capture video device: capture device for retrieving images.
> +
> +
> +  - ISP4 Image Signal Processing Subdevice Node
> +
> +-----------------------------------------------
> +
> +The isp4 is represented as a single V4L2 subdev, the sub-device does not
> +provide interface to the user space. The sub-device is connected to one video node
> +(isp4_capture) with immutable active link. The isp entity is connected
> +to sensor pad 0 and receives the frames using CSI-2 protocol. The sub-device is
> +also responsible to configure CSI2-2 receiver.
> +The sub-device processes bayer raw data from the connected sensor and output
> +them to different YUV formats. The isp also has scaling capabilities.
> +
> +  - isp4_capture - Frames Capture Video Node
> +
> +--------------------------------------------
> +
> +Isp4_capture is a capture device to capture frames to memory.
> +This entity is the DMA engine that write the frames to memory.
> +The entity is connected to isp4 sub-device.
> +
> +Capturing Video Frames Example
> +==============================
> +
> +.. code-block:: bash
> +
> +         # set the links
> +
> +         # start streaming:
> +         v4l2-ctl "-d" "/dev/video0" "--set-fmt-video=width=1920,height=1080,pixelformat=NV12" "--stream-mmap" "--stream-count=10"
> diff --git a/Documentation/admin-guide/media/amdisp4.dot b/Documentation/admin-guide/media/amdisp4.dot
> new file mode 100644
> index 000000000000..a4c2f0cceb30
> --- /dev/null
> +++ b/Documentation/admin-guide/media/amdisp4.dot
> @@ -0,0 +1,8 @@
> +digraph board {
> +	rankdir=TB
> +	n00000001 [label="{{<port0> 0} | amd isp4\n | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
> +	n00000001:port1 -> n00000004 [style=bold]
> +	n00000004 [label="Preview\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
> +	n0000000a [label="{{} | ov05c10 22-0010\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]

Does the driver still have a subdev for the sensor, or is that a
leftover ? Looking at the source code, I don't see where the sensor
would be handled.

> +	n0000000a:port0 -> n00000001:port0 [style=bold]
> +}
> diff --git a/Documentation/admin-guide/media/v4l-drivers.rst b/Documentation/admin-guide/media/v4l-drivers.rst
> index 3bac5165b134..6027416e5373 100644
> --- a/Documentation/admin-guide/media/v4l-drivers.rst
> +++ b/Documentation/admin-guide/media/v4l-drivers.rst
> @@ -9,6 +9,7 @@ Video4Linux (V4L) driver-specific documentation
>  .. toctree::
>  	:maxdepth: 2
>  
> +	amdisp4-1
>  	bttv
>  	c3-isp
>  	cafe_ccic
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7724620896e7..72ef7c77d881 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1139,6 +1139,8 @@ M:	Nirujogi Pratap <pratap.nirujogi@....com>
>  L:	linux-media@...r.kernel.org
>  S:	Maintained
>  T:	git git://linuxtv.org/media.git
> +F:	Documentation/admin-guide/media/amdisp4-1.rst
> +F:	Documentation/admin-guide/media/amdisp4.dot
>  F:	drivers/media/platform/amd/Kconfig
>  F:	drivers/media/platform/amd/Makefile
>  F:	drivers/media/platform/amd/isp4/Kconfig

-- 
Regards,

Laurent Pinchart

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