Date:   Mon, 2 Oct 2023 16:36:32 +0200
From:   "Linux regression tracking (Thorsten Leemhuis)" 
        <regressions@...mhuis.info>
To:     Mario Limonciello <mario.limonciello@....com>,
        Linux regressions mailing list <regressions@...ts.linux.dev>,
        Mark Brown <broonie@...nel.org>
Cc:     Sven Frotscher <sven.frotscher@...il.com>, git@...ustwikerfors.se,
        alsa-devel@...a-project.org, lgirdwood@...il.com,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Takashi Iwai <tiwai@...e.com>
Subject: Re: [PATCH v4] ASoC: amd: yc: Fix non-functional mic on Lenovo 82YM

On 02.10.23 16:20, Mario Limonciello wrote:
> On 10/2/2023 09:13, Linux regression tracking (Thorsten Leemhuis) wrote:
>> On 02.10.23 15:47, Mario Limonciello wrote:
>>> On 10/2/2023 06:52, Mark Brown wrote:
>>>> On Mon, Oct 02, 2023 at 11:32:48AM +0200, Linux regression tracking
>>>> (Thorsten Leemhuis) wrote:
>>>>
>>>>> Makes me wonder: How many more such quirk entries will be needed? Will
>>>>> we have all machines listed soon, or do we expect that future Lenovo
>>>>> hardware will need entries as well? If it's the latter: are quirks
>>>>> really the right solution here, or do they just hide some bug or then
>>>>> need for code that automatically handles things?
>>>>
>>>> x86 firmware descriptions are terrible, it's just an endless procession
>>>> of quirks.  The model for ACPI is not to describe key information in
>>>> the
>>>> kernel and instead on Windows load device specific information from
>>>> separately supplied tables.  On Linux that translates into these
>>>> endless
>>>> quirks, on Windows it's platform specific drivers for otherwise generic
>>>> audio hardware.
>>>
>>> I knew there was a TON of "82" prefix systems from Lenovo so it was an
>>> educated guess that all of them needed DMIC support.  This was incorrect
>>> because one of them didn't have DMIC and that caused a no mic support
>>> problem on that system.
>>>
>>> So in the case of this seemingly endless list of systems being added to
>>> enable DMIC support Mark is right, Windows does it differently.
>>
>> Now I understand things better, many thx. But please allow me one more
>> question from the cheap seats:
>>
>> Seems before c008323fe361 things worked for a lot of systems for about
>> one year thx to 2232b2dd8cd4 (which added the wide "82" prefix quirk).
>> We then made that one machine work with c008323fe361, but broke a lot of
>> others with it that now need to be fixed with additional quirks; that
>> "TON of 82 prefix systems" sounds like we might not be close to the end
>> of that journey.
>>
>> So can't we just do it the other way around and assume DMIC support on
>> Lenovo 82* machines, except on those where we know it to cause trouble?
>>
>> Again: you are the experts here. If you are positive that we soon got
>> all machines covered where c008323fe361 causes a regression, then I
>> guess it's best to continue the patch we're on.
> 
> I don't like lists

And I don't like if we let people run into regressions knowingly. ;)

> that enable something for a ton of systems and then
> lists that disable something for a subset of them.  This becomes
> difficult to maintain.

Well, I had more thought along the lines of "do enable DMIC on Lenovo
82*, unless the following dmi (the one from c008323fe361) matches". But
I assume that's not easy to realize with the quirks table, so I guess
that is out. Whatever.

Well, I rest my case. But I guess I might come back to this if multiple
additional regressions reports come it due to c008323fe361.

Ciao, Thorsten

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