linux-kernel - Re: [PATCH v1] ACPI: video: Fix missing backlight node creation on

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Message-ID: <f6afc998-f11e-4aac-a190-fbadb97e2d0c@kylinos.cn>
Date: Thu, 18 Sep 2025 08:36:30 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: hansg@...nel.org
Cc: lenb@...nel.org, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org, mario.limonciello@....com, rafael@...nel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH v1] ACPI: video: Fix missing backlight node creation on


在 2025/9/12 18:35, Zihuan Zhang 写道:
>> 1. There must be a GPU driver for these laptops somewhere?
>> Even if out of tree using a laptop without a GPU these days
>> just does not give a good user experience. So fix the GPU
>> driver to call acpi_video_register_backlight().
>>
>> Note acpi_video_register_backlight() is deliberately exported
>> without requiring the consuming out of tree kernel module to
>> be GPL to allow this.
>>
>> Other options would be:
>>
>> 2. Add some special heuristics for Zhaoxin CPUs,
>> the kernel already has a CPUID match mechanism for
>> things like this. This could potentially be combined
>> with a DMI system-vendor check to only do this special
>> case handling on e.g. Lenovo and Inspur laptops.
>>
>> 3. Instead of adding the CPU-id based special case
>> just outright use DMI quirks. In this case lets try
>> to use substring matches to cover multiple models
>> with a single entry so as to not grow the quirk
>> table too much.
>
> Got it, thanks!
>
> In fact, we have tried a few approaches (cmdline option, CPU-ID based quirk, and DMI quirk),
> and all of them work.
> I will sync this information with Zhaoxin to see which way they prefer.

Zhaoxin has confirmed that they will handle this through their own GPU 
driver,

so we don’t need to take any additional actions on our side.

Thanks!