linux-kernel - Re: [PATCH] ASoC: codecs: wsa884x: allow sharing reset GPIO

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Message-ID: <b35a21a2-6e69-4033-8d51-2b67b08ac7b3@linaro.org>
Date:   Wed, 18 Oct 2023 14:57:59 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Banajit Goswami <bgoswami@...cinc.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: codecs: wsa884x: allow sharing reset GPIO

On 18/10/2023 14:56, Mark Brown wrote:
> On Wed, Oct 18, 2023 at 02:38:00PM +0200, Krzysztof Kozlowski wrote:
>> On 18/10/2023 14:35, Mark Brown wrote:
> 
>>> How do the speakers coordinate?
> 
>> They don't and that's the generic problem of many Linux drivers. Not
>> only this one, but others as well.
> 
>> Device unbind (remove()) or runtime suspend of one speaker will affect
>> other speaker. I don't think any other drivers solved this, because this
>> is rather core's GPIO issue, thus I am not solving it here either. :(
> 
> I'd expect that the GPIO users should coordiante directly rather than
> rely on the GPIO API to do the coordination for them - there aren't
> enough semantics in the GPIO itself to do much more except possibly
> provide discovery services (which would be nice).  Look at how the
> regulator API manages multiple regulators sharing an enable GPIO for
> example, it adds an additional layer of reference counting when it
> identifies a shared GPIO.

OK, it is still regulator core, though. Not individual drivers problem.

Several other existing drivers have the same issue, so this should be
solved in a generic or shared way.

Best regards,
Krzysztof