linux-kernel - Re: [PATCH RFC 0/9] gpio: improve support for shared GPIOs

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Message-ID: <CAMRc=Md1Ve4hnYQOryYEXG6_HSPJrANrr9gj2FMzCwsD+q5Cuw@mail.gmail.com>
Date: Tue, 21 Oct 2025 16:42:11 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Mark Brown <broonie@...nel.org>
Cc: linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, Srinivas Kandagatla <srini@...nel.org>, 
	Kees Cook <kees@...nel.org>, Mika Westerberg <westeri@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jaroslav Kysela <perex@...ex.cz>, Catalin Marinas <catalin.marinas@....com>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Takashi Iwai <tiwai@...e.com>, Rob Herring <robh@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Andy Shevchenko <andy@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, Will Deacon <will@...nel.org>, 
	Liam Girdwood <lgirdwood@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Manivannan Sadhasivam <mani@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, 
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH RFC 0/9] gpio: improve support for shared GPIOs

On Tue, Oct 21, 2025 at 4:08 PM Mark Brown <broonie@...nel.org> wrote:
>
> On Mon, Oct 20, 2025 at 11:41:52AM +0200, Bartosz Golaszewski wrote:
> > On Fri, Oct 17, 2025 at 7:32 PM Mark Brown <broonie@...nel.org> wrote:
>
> > > It really should be the actual physical state change that triggers the
> > > event.
>
> > I guess so, but this would require some non-trivial rework of the
> > regulator core. We'd need some list of deferred notifications stored
> > in memory for when the physical state actually changes.
>
> I'm not sure I see the need for deferred notifications?  We'd need to go
> round all the users whenever a physical change to the GPIO happens but
> it's not clear what we'd need to store beyond the list of users?

In my mind I was thinking that we only need to send the notifications
to users who already enabled/disabled the regulator too but you're
right, it seems like a loop over the relevant pins should be enough.

In any case: this is outside the scope of this series but I'll see if
it's easy enough to add separately.

Bartosz