linux-kernel - Re: [PATCH v3] dt-bindings: gpio: add common consumer GPIO lines

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Date:   Fri, 1 Apr 2022 14:44:43 -0500
From:   Rob Herring <robh@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        devicetree@...r.kernel.org,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [PATCH v3] dt-bindings: gpio: add common consumer GPIO lines

On Fri, Apr 01, 2022 at 05:11:57PM +0200, Krzysztof Kozlowski wrote:
> On 01/04/2022 17:01, Rob Herring wrote:
> > On Fri, Apr 1, 2022 at 8:27 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski@...aro.org> wrote:
> >>
> >> On 01/04/2022 15:13, Rob Herring wrote:
> >>> On Fri, 01 Apr 2022 09:27:14 +0200, Krzysztof Kozlowski wrote:
> >>>> Typical GPIO lines like enable, powerdown, reset or wakeup are not
> >>>> documented as common, which leads to new variations of these (e.g.
> >>>> pwdn-gpios).  Add a common schema which serves also as a documentation
> >>>> for preferred naming.
> >>>>
> >>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >>>>
> >>>> ---
> >>>>
> >>>> Changes since v2:
> >>>> 1. Correct email.
> >>>>
> >>>> Changes since v1:
> >>>> 1. Select-true, add maxItems and description for each entry (Rob).
> >>>> 2. Mention ACTIVE_LOW in bindings description (Linus).
> >>>> 3. Add allOf for pwrseq reset-gpios case.
> >>>>
> >>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >>>> ---
> >>>>  .../bindings/gpio/gpio-consumer-common.yaml   | 64 +++++++++++++++++++
> >>>>  1 file changed, 64 insertions(+)
> >>>>  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-consumer-common.yaml
> >>>>
> >>>
> >>> My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> >>> on your patch (DT_CHECKER_FLAGS is new in v5.13):
> >>>
> >>> yamllint warnings/errors:
> >>>
> >>> dtschema/dtc warnings/errors:
> >>> /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/regulator/richtek,rt4801-regulator.example.dt.yaml: rt4801@73: enable-gpios: [[4294967295, 2, 0], [4294967295, 3, 0]] is too long
> >>>       From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/gpio/gpio-consumer-common.yaml
> >>>
> >>
> >> Hi Rob,
> >>
> >> With v1, you proposed to use maxItems for all these standard gpios, but
> >> as we see here there are two exceptions:
> >> 1. pwrseq might have up to 32 reset-gpios,
> >> 2. richtek,rt4801 uses up to 2 enable-gpios.
> > 
> > There's always an outlier...
> > 
> >> One way is to add exceptions in gpio-consumer-common.yaml, like I did
> >> for reset-gpios and pwrseq. However this scales poor if more of such
> >> usages appear.
> > 
> > I'd reject any new cases, but even just 2 I don't really like.
> 
> The richtek,rt4801 enable-gpios are for controlling two separate
> regulators, so it should have been under regulator subnodes/children.
> Some other regulators follow this pattern, so only this one is done that
> way.
> 
> That driver could be converted to enable-gpios per regulator, so if you
> are sure about rejection of new cases, how about keeping current
> exceptions in allOf:if?

Okay.

Rob