linux-kernel - Re: [PATCH 02/23] dt-bindings: gpio: nomadik: add optional ngpios property

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Message-Id: <CZ954Q11FWMI.39QMRYTRZAO1C@bootlin.com>
Date: Mon, 19 Feb 2024 15:55:06 +0100
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: "Linus Walleij" <linus.walleij@...aro.org>
Cc: "Bartosz Golaszewski" <brgl@...ev.pl>, "Rob Herring"
 <robh+dt@...nel.org>, "Krzysztof Kozlowski"
 <krzysztof.kozlowski+dt@...aro.org>, "Conor Dooley" <conor+dt@...nel.org>,
 "Philipp Zabel" <p.zabel@...gutronix.de>, "Thomas Bogendoerfer"
 <tsbogend@...ha.franken.de>, <linux-gpio@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-arm-kernel@...ts.infradead.org>, <linux-mips@...r.kernel.org>,
 "Gregory CLEMENT" <gregory.clement@...tlin.com>, "Vladimir Kondratiev"
 <vladimir.kondratiev@...ileye.com>, "Thomas Petazzoni"
 <thomas.petazzoni@...tlin.com>, "Tawfik Bayouk"
 <tawfik.bayouk@...ileye.com>
Subject: Re: [PATCH 02/23] dt-bindings: gpio: nomadik: add optional ngpios
 property

Hello,

On Mon Feb 19, 2024 at 3:50 PM CET, Linus Walleij wrote:
> On Wed, Feb 14, 2024 at 5:24 PM Théo Lebrun <theo.lebrun@...tlin.com> wrote:
>
> > This GPIO controller can support a lesser number of GPIOs than 32.
> > Express that in devicetree using an optional, generic property.
> >
> > Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
> > ---
> >  Documentation/devicetree/bindings/gpio/st,nomadik-gpio.yaml | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/st,nomadik-gpio.yaml b/Documentation/devicetree/bindings/gpio/st,nomadik-gpio.yaml
> > index a999908173d2..bbd23daed229 100644
> > --- a/Documentation/devicetree/bindings/gpio/st,nomadik-gpio.yaml
> > +++ b/Documentation/devicetree/bindings/gpio/st,nomadik-gpio.yaml
> > @@ -50,6 +50,10 @@ properties:
> >    gpio-ranges:
> >      maxItems: 1
> >
> > +  ngpios:
> > +    minimum: 0
> > +    maximum: 32
>
> I can't help but wonder what good is ngpios = <0>; but OK.
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

A min value is required, else it is equal to the max. There was no
reason to pick anything bigger than zero.

I'll admit it is not a setup I have tested so the driver might have
issues with the ngpios==0 edge-case. Of course I do not expect anyone
to care.

Regards,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com