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

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Message-ID: <64dd0bab-6036-4e06-aff5-b0f86a167ada@kernel.org>
Date: Tue, 7 Oct 2025 10:14:14 +0900
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>,
 Markus Probst <markus.probst@...teo.de>
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 03/10/2025 17:51, Bartosz Golaszewski wrote:
> 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?


There is no such property as acpi-path and I don't see here any ABI
being documented. Nothing in dtschema, either. Nothing in DT spec. I
also did not receive this patch. Actually - nothing from
markus.probst@...teo.de in mail mailbox.

So no clue what is this about, but if you want to use undocumented
property then obviously no.


Best regards,
Krzysztof