linux-kernel - Re: [PATCH v7 2/6] media: admin-guide: Add starfive

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Message-ID: <c7aaf817-3504-e325-c29b-5cf1834ae72f@starfivetech.com>
Date:   Thu, 27 Jul 2023 06:26:17 +0800
From:   Jack Zhu <jack.zhu@...rfivetech.com>
To:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Foss <rfoss@...nel.org>,
        Todor Tomov <todor.too@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Eugen Hristev <eugen.hristev@...labora.com>,
        Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
CC:     <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <changhuang.liang@...rfivetech.com>
Subject: Re: [PATCH v7 2/6] media: admin-guide: Add starfive_camss.rst for
 Starfive Camera Subsystem

Hi Bryan,

Thank you for your comments.

On 2023/7/26 19:26, Bryan O'Donoghue wrote:
> On 19/06/2023 12:28, Jack Zhu wrote:
>> Add starfive_camss.rst file that documents the Starfive Camera
>> Subsystem driver which is used for handing image sensor data.
>>
>> Signed-off-by: Jack Zhu <jack.zhu@...rfivetech.com>
>> ---
>>   .../admin-guide/media/starfive_camss.rst      | 57 +++++++++++++++++++
>>   .../media/starfive_camss_graph.dot            | 16 ++++++
>>   .../admin-guide/media/v4l-drivers.rst         |  1 +
>>   MAINTAINERS                                   |  1 +
>>   4 files changed, 75 insertions(+)
>>   create mode 100644 Documentation/admin-guide/media/starfive_camss.rst
>>   create mode 100644 Documentation/admin-guide/media/starfive_camss_graph.dot
>>
>> diff --git a/Documentation/admin-guide/media/starfive_camss.rst b/Documentation/admin-guide/media/starfive_camss.rst
>> new file mode 100644
>> index 000000000000..a6378849384f
>> --- /dev/null
>> +++ b/Documentation/admin-guide/media/starfive_camss.rst
>> @@ -0,0 +1,57 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +.. include:: <isonum.txt>
>> +
>> +================================
>> +Starfive Camera Subsystem driver
>> +================================
>> +
>> +Introduction
>> +------------
>> +
>> +This file documents the driver for the Starfive Camera Subsystem found on
>> +Starfive JH7110 SoC. The driver is located under drivers/media/platform/
>> +starfive.
>> +
>> +The driver implements V4L2, Media controller and v4l2_subdev interfaces.
>> +Camera sensor using V4L2 subdev interface in the kernel is supported.
>> +
>> +The driver has been successfully used on the Gstreamer 1.18.5 with
>> +v4l2src plugin.
>> +
>> +
>> +Starfive Camera Subsystem hardware
>> +----------------------------------
>> +
>> +The Starfive Camera Subsystem hardware consists of:
>> +
>> +- MIPI DPHY Receiver: receives mipi data from a MIPI camera sensor.
> 
> Feels like a terribe nit-pick but you have "mipi" and "MIPI" here. I'd be consistent with one - recommend MIPI throughout your documentation.
> 

Okay, I will keep a consistent description.

>> +- MIPI CSIRx Controller: is responsible for handling and decoding CSI2 protocol
>> +  based camera sensor data stream.
>> +- ISP: handles the image data streams from the MIPI CSIRx Controller.
> 
> Maybe you've done this elsewhere but, it would be worthwhile describing what the ISP does. Debayering ? 3As ? Just raw dumps ?
> 

Ok, I will add more descriptions in the next version.

>> +- VIN(Video In): a top-level module, is responsible for controlling power
>> +  and clocks to other modules, dumps the input data to memory or transfers the
>> +  input data to ISP.
>> +
>> +
>> +Topology
>> +--------
>> +
>> +The media controller pipeline graph is as follows:
>> +
>> +.. _starfive_camss_graph:
>> +
>> +.. kernel-figure:: starfive_camss_graph.dot
>> +    :alt:   starfive_camss_graph.dot
>> +    :align: center
>> +
>> +The driver has 2 video devices:
>> +
>> +- stf_vin0_wr_video0: capture device for images directly from the VIN module.
> 
> OK so you can get the raw images.
> 
>> +- stf_vin0_isp0_video1: capture device for images without scaling.
>> +
>> +The driver has 3 subdevices:
>> +
>> +- stf_isp0: is responsible for all the isp operations.
>> +- stf_vin0_wr: used to dump RAW images to memory.
>> +- stf_vin0_isp0: used to capture images for the stf_vin0_isp0_video1 device.
> 
> But what is being output here ? RGB, jpeg, YUV ?
> It would be worth adding a few bits of text to describe that so you don't have to dive into code to understand it.
> 

Ok, I will add more descriptions.

> ---
> bod

-- 
Regards,

Jack Zhu