linux-kernel - Re: [PATCH] gpio: of: make it possible to reference gpios probed in acpi in device tree

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Message-ID: <CAMRc=McioBjF3WCBu0ezzuL+JJTiEpF2fz1YpbToRpijpHfAEg@mail.gmail.com>
Date: Fri, 3 Oct 2025 10:51:31 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Markus Probst <markus.probst@...teo.de>, Krzysztof Kozlowski <krzk@...nel.org>
Cc: Linus Walleij <linus.walleij@...aro.org>, Mika Westerberg <westeri@...nel.org>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, linux-gpio@...r.kernel.org, 
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: of: make it possible to reference gpios probed in
 acpi in device tree

On Fri, Oct 3, 2025 at 10:40 AM Markus Probst <markus.probst@...teo.de> wrote:
>
> On Fri, 2025-10-03 at 10:03 +0200, Bartosz Golaszewski wrote:
> > On Thu, Oct 2, 2025 at 11:58 PM Markus Probst
> > <markus.probst@...teo.de> wrote:
> > >
> > > sometimes it is necessary to use both acpi and device tree to
> > > declare
> >
> > This is a rather controversial change so "sometimes" is not
> > convincing
> > me. I would like to see a user of this added in upstream to consider
> > it.
> >
> > > devices. Not every gpio device driver which has an acpi_match_table
> > > has
> > > an of_match table (e.g. amd-pinctrl). Furthermore gpio is an device
> > > which
> >
> > What is the use-case here because I'm unable to wrap my head around
> > it? Referencing devices described in ACPI from DT? How would the
> > associated DT source look like?
> In my specific usecase for the Synology DS923+, there are gpios for
> powering the usb vbus on (powered down by default), also for powering
> on sata disks. An example for a regulator defined in DT using a gpio in
> ACPI (in this case controlling the power of on of the usb ports):
>
>         gpio: gpio-controller@...81500 {
>                 acpi-path = "\\_SB_.GPIO";
>                 #gpio-cells = <2>;
>         };
>
>         vbus1_regulator: fixedregulator@0 {
>                 compatible = "regulator-fixed";
>                 regulator-name = "vbus1_regulator";
>                 regulator-min-microvolt = <5000000>;
>                 regulator-max-microvolt = <5000000>;
>                 gpio = <&gpio 0x2a 0x01>;
>         };
>
> - Markus Probst
> >

Krzysztof: Could you please look at this and chime in? Does this make any sense?

> > Bart
> >
> > > can't be easily disabled in acpi and then redeclared in device
> > > tree, as
> > > it often gets used by other devices declared in acpi (e.g. via
> > > GpioInt or
> > > GpioIo). Thus a disable of acpi and migration to device tree is not
> > > always
> > > possible or very time consuming, while acpi by itself is very
> > > limited and
> > > not always sufficient. This won't affect most configurations, as
> > > most of
> > > the time either CONFIG_ACPI or CONFIG_OF gets enabled, not both.
> > >
> > > Signed-off-by: Markus Probst <markus.probst@...teo.de>
> > > ---
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >

[snip]

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