Re: [PATCH v3 7/7] Documentation: add documentation of AMD isp 4 driver

["Du, Bin" <bin.du@amd.com>]

Thanks Laurent Pinchart for your careful review.

On 9/3/2025 6:04 PM, Laurent Pinchart wrote:
> 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@amd.com>
>> Signed-off-by: Svetoslav Stoilov <Svetoslav.Stoilov@amd.com>
>> Signed-off-by: Bin Du <Bin.Du@amd.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.
> 

Yes, you are definitely correct, no sensor subdev anymore. My fault, i 
forgot to sync the document to the latest one, will update in the next 
version, really sorry for that.

>> +	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@amd.com>
>>   L:	linux-media@vger.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,
Bin