linux-kernel - Re: [PATCH v3 0/7] Add AMD ISP4 driver

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Message-ID: <485f202e-de42-48c0-bdae-52d6290fd7d3@amd.com>
Date: Wed, 10 Sep 2025 10:15:05 +0800
From: "Du, Bin" <bin.du@....com>
To: Shengyu Qu <wiagn233@...look.com>, mchehab@...nel.org,
 hverkuil@...all.nl, laurent.pinchart+renesas@...asonboard.com,
 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
Cc: 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
Subject: Re: [PATCH v3 0/7] Add AMD ISP4 driver

Hi Shengyu,

On 9/7/2025 2:40 AM, Shengyu Qu wrote:
> Hi,
> 
> 
>> Changes v2 -> v3:
>>
>> - All the dependent patches in other modules (drm/amd/amdgpu, 
>> platform/x86, pinctrl/amd) merged on upstream mainline kernel 
>> (https://github.com/torvalds/linux) v6.17.
>> - Removed usage of amdgpu structs in ISP driver. Added helper 
>> functions in amdgpu accepting opaque params from ISP driver to 
>> allocate and release ISP GART buffers.
>> - Moved sensor and MIPI phy control entirely into ISP FW instead of 
>> the previous hybrid approach controlling sensor from both FW and x86 
>> (sensor driver).
>> - Removed phy configuration and sensor binding as x86 (sensor driver) 
>> had relinquished the sensor control for ISP FW. With this approach the 
>> driver will be exposed as web camera like interface.
>> - New FW with built-in sensor driver is submitted on upstream linux- 
>> firmware repo (https://gitlab.com/kernel-firmware/linux-firmware/).
> 
> 
> The sensor is MIPI CSI and controlled by I2C, isn't it? Then why we put 
> all control logic into FW rather than driver? Any existing CSI camera 
> ISP support implementation are not doing this by FW.
> 

Yes, it's MIPI CSI sensor and controlled by I2C. In AMD ISP 3A algo 
architecture, part of the sensor control resides in the FW and in 
previous version, sensor init control is put in the sensor driver. With 
discussion with the V4L2 maintainer, the current approach starting from 
V3 is to move all sensor control into FW and remove the sensor driver 
dependency. Please refer to 
https://lore.kernel.org/all/63949b3b-ca2d-42aa-bc8d-43f2952d307a@amd.com/#t 
which provides the context and background on how we arrived at the 
current architectural change in v3.

> Cheers,
> Shengyu

-- 
Regards,
Bin