Date:   Thu, 11 Nov 2021 14:06:04 -0600
From:   Rob Herring <robh@kernel.org>
To:     =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>
Subject: Re: [PATCH RFC] dt-bindings: pinctrl: support specifying pins
Message-ID: <YY13rKxQpzcB4f0b@robh.at.kernel.org>
References: <20211110231436.8866-1-zajec5@gmail.com>
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On Thu, Nov 11, 2021 at 12:14:36AM +0100, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Add support for "pins" node with pin@ subnodes. This allows specifying
> all pins (and their names) at DT level.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> While working with pinctrl in Linux I started wondering if we could
> start specifying pins in DT instead of Linux drivers. When working with
> DT we usually avoid hardcoding hardware description in drivers so it
> isn't clear to me why it doesn't apply to pins.
> 
> Please let me know if this makes sense. If by some chance I'm correct I
> think that specifying groups and functions could follow too.
> 
> FWIW: I didn't start working on Linux reading pins from DT yet.
> ---
>  .../bindings/pinctrl/brcm,ns-pinmux.yaml      | 12 +++++++++-
>  .../devicetree/bindings/pinctrl/pinctrl.yaml  | 23 +++++++++++++++++++
>  2 files changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/pinctrl/brcm,ns-pinmux.yaml b/Documentation/devicetree/bindings/pinctrl/brcm,ns-pinmux.yaml
> index 8d1e5b1cdd5f..92a86b0822d6 100644
> --- a/Documentation/devicetree/bindings/pinctrl/brcm,ns-pinmux.yaml
> +++ b/Documentation/devicetree/bindings/pinctrl/brcm,ns-pinmux.yaml
> @@ -74,7 +74,7 @@ required:
>    - reg
>    - reg-names
>  
> -additionalProperties: false
> +unevaluatedProperties: false
>  
>  examples:
>    - |
> @@ -83,6 +83,16 @@ examples:
>          reg = <0x1800c1c0 0x24>;
>          reg-names = "cru_gpio_control";
>  
> +        pins {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            pin@0 {
> +                reg = <0>;

Where does 'reg' value come from?

> +                label = "spi_clk";
> +            };

If you just want a list of pins names, then why not just a list of 
names?

Rob