Re: [RFC 5/9] dt-bindings: arm: samsung: Convert Exynos PMU bindings to json-schema

[Krzysztof Kozlowski]

On Tue, 3 Sep 2019 at 10:25, Rob Herring <robh+dt@xxxxxxxxxx> wrote:
>
> On Tue, Sep 3, 2019 at 8:58 AM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> >
> > On Mon, 26 Aug 2019 at 13:54, Rob Herring <robh+dt@xxxxxxxxxx> wrote:
> > >
> > > On Fri, Aug 23, 2019 at 9:54 AM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> > > >
> > > > Convert Samsung Exynos Power Management Unit (PMU) bindings to DT schema
> > > > format using json-schema.
> > > >
> > > > Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> > > > ---
> > > >  .../devicetree/bindings/arm/samsung/pmu.txt   | 72 --------------
> > > >  .../devicetree/bindings/arm/samsung/pmu.yaml  | 93 +++++++++++++++++++
> > > >  2 files changed, 93 insertions(+), 72 deletions(-)
> > > >  delete mode 100644 Documentation/devicetree/bindings/arm/samsung/pmu.txt
> > > >  create mode 100644 Documentation/devicetree/bindings/arm/samsung/pmu.yaml
> > >
> > >
> > > > diff --git a/Documentation/devicetree/bindings/arm/samsung/pmu.yaml b/Documentation/devicetree/bindings/arm/samsung/pmu.yaml
> > > > new file mode 100644
> > > > index 000000000000..818c6f3488ef
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/arm/samsung/pmu.yaml
> > > > @@ -0,0 +1,93 @@
> > > > +# SPDX-License-Identifier: GPL-2.0
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/arm/samsung/pmu.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Samsung Exynos SoC series Power Management Unit (PMU)
> > > > +
> > > > +maintainers:
> > > > +  - Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    items:
> > > > +      - enum:
> > > > +          - samsung,exynos3250-pmu
> > > > +          - samsung,exynos4210-pmu
> > > > +          - samsung,exynos4412-pmu
> > > > +          - samsung,exynos5250-pmu
> > > > +          - samsung,exynos5260-pmu
> > > > +          - samsung,exynos5410-pmu
> > > > +          - samsung,exynos5420-pmu
> > > > +          - samsung,exynos5433-pmu
> > > > +          - samsung,exynos7-pmu
> > > > +      - const: syscon
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  '#clock-cells':
> > > > +    const: 1
> > > > +
> > > > +  clock-names:
> > > > +    description:
> > > > +      list of clock names for particular CLKOUT mux inputs
> > > > +    # TODO: what is the maximum number of elements (mux inputs)?
> > > > +    minItems: 1
> > > > +    maxItems: 32
> > > > +    items:
> > > > +      - enum:
> > >
> > > This isn't correct as you are only defining possible names for the
> > > first item. Drop the '-' (making items a schema instead of a list) and
> > > then it applies to all. However, doing that will cause a meta-schema
> > > error which I need to fix to allow. Or if there's a small set of
> > > possibilities of number of inputs, you can list them under a 'oneOf'
> > > list.
> >
> > Mhmm, I cannot test it or I have an error in the schema. if I
> > understand correctly, this would be:
> >
> >   clock-names:
> >     description:
> >       List of clock names for particular CLKOUT mux inputs
> >     minItems: 1
> >     maxItems: 16
> >     items:
> >       clkout0
> >       clkout1
> >       clkout2
> >       clkout3
> >       clkout4
> >       clkout5
> >       clkout6
> >       clkout7
> >       clkout8
> >       clkout9
> >       clkout10
> >       clkout11
> >       clkout12
> >       clkout13
> >       clkout14
> >       clkout15
> >       clkout16
> >
> > Now it produces the error "ignoring, error in schema 'items'" but
> > maybe it is expected with current meta-schema?
>
> 'make dt_binding_check' will give more detailed errors.
>
> Are the inputs always contiguous 0-N? If so, you want:
>
> items:
>   - const: clkout0
>   - const: clkout1
>   - const: clkout2
>   ...
>
> If you want to express any number and order of strings is valid, then you need:
>
> items:
>   enum:
>     - clkout0
>     - clkout1
>     - clkout2
>
> Doing that is discouraged for bindings though. Currently, it will
> generate an error from the meta-schema, but we could change that.

It's the second case. The inputs are not contiguous. Examples:

system-controller {
    compatible = "samsung,exynos3250-pmu", "syscon";
    clock-names = "clkout8";
    clocks = <&cmu CLK_FIN_PLL>;
}

system-controller {
    compatible = "samsung,exynos4412-pmu", "syscon";
    clock-names = "clkout0", "clkout1", "clkout2", "clkout3",
                  "clkout4", "clkout8", "clkout9";
    clocks = <&clock CLK_OUT_DMC>, <&clock CLK_OUT_TOP>,
             <&clock CLK_OUT_LEFTBUS>, <&clock CLK_OUT_RIGHTBUS>,
             <&clock CLK_OUT_CPU>, <&clock CLK_XXTI>, <&clock CLK_XUSBXTI>;
}

The bindings never required any specific ordering. Also the driver
just go through all indices and parses them.

Your second syntax fails:
Documentation/devicetree/bindings/arm/samsung/pmu.yaml:
properties:clock-names:items: {'enum': ['clkout0', 'clkout1',
'clkout2', 'clkout3', 'clkout4', 'clkout5', 'clkout6', 'clkout7',
'clkout8', 'clkout9', 'clkout10', 'clkout11', 'clkout12', 'clkout13',
'clkout14', 'clkout15', 'clkout16']} is not of type 'array'

Best regards,
Krzysztof