linux-kernel - Re: [PATCH 2/3] dt-bindings: gpio: Convert UniPhier GPIO to json-schema

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Date:   Mon, 24 Feb 2020 08:51:50 -0600
From:   Rob Herring <robh@...nel.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     DTML <devicetree@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] dt-bindings: gpio: Convert UniPhier GPIO to json-schema

On Fri, Feb 21, 2020 at 11:33 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Hi Rob,
>
> On Sat, Feb 22, 2020 at 12:32 AM Rob Herring <robh@...nel.org> wrote:
> >
> > On Fri, 21 Feb 2020 11:10:01 +0900, Masahiro Yamada wrote:
> > > Convert the UniPhier GPIO controller binding to DT schema format.
> > >
> > > I omitted the 'gpio-ranges' property because it is defined in the
> > > dt-schema project (/schemas/gpio/gpio.yaml).
> > >
> > > As of writing, the 'gpio-ranges-group-names' is not defined in that
> > > file despite it is a common property described in
> > > Documentation/devicetree/bindings/gpio/gpio.txt
> > > So, I defined it in this schema.
> > >
> > > Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> > > ---
> > >
> > > I have a question about the range about 'ngpio'.
> > >
> > >   ngpios:
> > >     minimum: 0
> > >     maximum: 512
> > >
> > > The 'ngpio' property is already defined as 'uint32' in the dt-schema tool:
> > > https://github.com/robherring/dt-schema/blob/master/schemas/gpio/gpio.yaml#L20
> > >
> > > 'uint32' is unsigned, so 'minimum: 0' looks too obvious.
> > >
> > > I cannot omit the minimum because minimum and maximum depend on each other.
> > > I just put a sensible number, 512, in maximum.
> > >
> > > If this range is entirely unneeded, I will delete it.
> >
> > This property is generally for when you can have some number less
> > than a maximum number implied by the compatible string.
> >
> > If there is really no max (e.g. 2^32 - 1 is valid), then just do
> > 'ngpios: true'
>
>
> What does ': true' mean?

It's a schema that always passes validation. It's purpose here is just
to say you are using this common property for this binding.

>
> If it is documented somewhere,
> could you point me to the reference?

https://github.com/devicetree-org/dt-schema/blob/master/schemas/gpio/gpio.yaml

>
> Even if I remove the 'ngpio' entirely
> from my dt-schema, the 'ngpio' is checked
> correctly.

Yes, if you change it to a string value for example, it should fail.
(Only if DT_SCHEMA_FILES is not set without my kbuild changes)

You should also add 'additionalProperties: false' at the top level of
your schema and then it will also fail if you don't list ngpios in
properties.

Rob