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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b7aeda24-d638-45b7-8e30-80d287f498f8@sirena.org.uk>
Date:   Wed, 18 Oct 2023 13:56:11 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.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 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.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)