linux-kernel - Re: [PATCH v2 2/2] gpio: aggregator: add gpio-aggregator DT compatible

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Message-ID: <CAMRc=MfgoKmsNAmn3rO2jDL-ZArMX2Jh-n4SnV6rpzRY3KSwuA@mail.gmail.com>
Date: Wed, 11 Feb 2026 10:47:42 +0100
From: Bartosz Golaszewski <brgl@...nel.org>
To: James Hilliard <james.hilliard1@...il.com>
Cc: linux-gpio@...r.kernel.org, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Linus Walleij <linusw@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Alexander Stein <linux@...tq-group.com>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] gpio: aggregator: add gpio-aggregator DT compatible

On Wed, Feb 11, 2026 at 9:14 AM James Hilliard
<james.hilliard1@...il.com> wrote:
>
> Add an OF match entry for "gpio-aggregator" to support plain GPIO
> forwarding from devicetree without delay semantics.
>
> This allows exposing selected lines as a logical GPIO controller with
> stable aggregated offsets, so consumers can reference forwarded lines
> instead of physical controller offsets. It also allows creating bundled
> groups of named lines that can be exposed to userspace as a convenient
> virtual gpiochip interface. Using "gpio-delay" for this case is not
> suitable because it enables delay features and requires 3-cell GPIO
> specifiers.
>
> Signed-off-by: James Hilliard <james.hilliard1@...il.com>
> ---
> Changes v1 -> v2:
>   - Split DT schema into a separate patch
>     (suggested by Krzysztof Kozlowski)
>   - Expand commit message rationale and use-case explanation
>     (suggested by Krzysztof Kozlowski)
>   - Clarify userspace use case with bundled named line groups
> ---
>  drivers/gpio/gpio-aggregator.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
> index 416f265d09d0..a09752fc5fe2 100644
> --- a/drivers/gpio/gpio-aggregator.c
> +++ b/drivers/gpio/gpio-aggregator.c
> @@ -1635,6 +1635,9 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
>  }
>
>  static const struct of_device_id gpio_aggregator_dt_ids[] = {
> +       {
> +               .compatible = "gpio-aggregator",
> +       },
>         {
>                 .compatible = "gpio-delay",
>                 .data = (void *)FWD_FEATURE_DELAY,
> --
> 2.43.0
>

Regardless of the DT bindings - this change is perfectly fine. We do
that for other "virtual" devices like gpio-sim, gpio-virtuser, etc. I
would just ask you to document it under
Documentation/admin-guide/gpio/gpio-aggregator.rst.

Bartosz