Re: [PATCH v4 1/3] dt-bindings: iio: adc: sophgo,cv18xx-saradc.yaml: Add Sophgo CV18XX SARADC binding

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 6060 bytes --]

On Tue, Aug 20, 2024 at 06:21:07PM +0200, Thomas Bonnefille wrote:
> Hello Conor,
> 
> On 8/12/24 5:53 PM, Conor Dooley wrote:
> > On Mon, Aug 12, 2024 at 05:00:55PM +0200, Thomas Bonnefille wrote:
> > > The Sophgo SARADC is a Successive Approximation ADC that can be found in
> > > the Sophgo SoC.
> > > 
> > > Signed-off-by: Thomas Bonnefille <thomas.bonnefille@bootlin.com>
> > > ---
> > >   .../bindings/iio/adc/sophgo,cv18xx-saradc.yaml     | 85 ++++++++++++++++++++++
> > >   1 file changed, 85 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/sophgo,cv18xx-saradc.yaml b/Documentation/devicetree/bindings/iio/adc/sophgo,cv18xx-saradc.yaml
> > > new file mode 100644
> > > index 000000000000..846590808e5f
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/sophgo,cv18xx-saradc.yaml
> > > @@ -0,0 +1,85 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/iio/adc/sophgo,cv18xx-saradc.yaml#
> > 
> > Filename matching the compatible please.
> > 
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title:
> > > +  Sophgo CV18XX SoC series 3 channels Successive Approximation Analog to
> > > +  Digital Converters
> > > +
> > > +maintainers:
> > > +  - Thomas Bonnefille <thomas.bonnefille@bootlin.com>
> > > +
> > > +description:
> > > +  Datasheet at https://github.com/sophgo/sophgo-doc/releases
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: sophgo,cv1800b-saradc
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  clocks:
> > > +    maxItems: 1
> > > +
> > > +  '#address-cells':
> > > +    const: 1
> > > +
> > > +  '#size-cells':
> > > +    const: 0
> > > +
> > > +patternProperties:
> > > +  "^channel@[0-3]+$":
> > > +    $ref: adc.yaml
> > > +
> > > +    description: |
> > 
> > This | is not required.
> > 
> > > +      Represents the channels of the ADC.
> > > +
> > > +    properties:
> > > +      reg:
> > > +        description: |
> > > +          The channel number. It can have up to 3 channels numbered from 0 to 2.
> > > +        items:
> > > +          - minimum: 0
> > > +            maximum: 2
> > 
> > Is this sufficient to limit the number of channels to 3? Aren't you relying
> > on the unique unit addresses warning in dtc to limit it, rather than
> > actually limiting with min/maxItems?
> > 
> It seems like I can't use min/maxItems on this property. I think that it is
> using size-cells + address-cells to deduce that the number of items should
> be equal to 1.

I think I was mistaken in talking about mix/max items here. I had the
right idea, but mentioned an incorrect solution - sorry about that. I
wasn't talking about the number of elements in the reg property, what I
meant was limiting the number of channel nodes in the first place -
something which min/maxItems cannot do. As examples of the problem I was
thinking of, see the below two examples:

    adc@30f0000 {
        compatible = "sophgo,cv1800b-saradc";
        reg = <0x030f0000 0x1000>;
        clocks = <&clk CLK_SARADC>;
        interrupts = <100 IRQ_TYPE_LEVEL_HIGH>;
        #address-cells = <1>;
        #size-cells = <0>;

        channel@0 {
            reg = <0>;
        };
        channel@2 {
            reg = <2>;
        };
        channel@22 {
            reg = <2>;
        };
    };

    adc@30f0000 {
        compatible = "sophgo,cv1800b-saradc";
        reg = <0x030f0000 0x1000>;
        clocks = <&clk CLK_SARADC>;
        interrupts = <100 IRQ_TYPE_LEVEL_HIGH>;
        #address-cells = <1>;
        #size-cells = <0>;

        channel@0 {
            reg = <0>;
        };
        channel@2 {
            reg = <2>;
        };
        channel@22 {
            reg = <2>;
        };
    };

The solution is simple, remove the + from the regex. Sorry for sending
you on the wrong track Thomas.

Thanks,
Conor.

> Looking at the dtschema repository it seems to be the case in reg.yaml with
> address-cells/size-cells = 2/2, 1/1 and 2/1.
> If I try to use maxItems here :
> 
>     properties:
>       reg:
>         maxItems: 1
>         items:
>           - minimum: 0
>             maximum: 2
> 
> I get this strange error message from `make dt_binding_check`:
> 
> DTEX
> Documentation/devicetree/bindings/iio/adc/sophgo,cv1800b-saradc.example.dts
> /home/thomas/linux/Documentation/devicetree/bindings/iio/adc/sophgo,cv1800b-saradc.yaml:
> patternProperties:^channel@[0-2]+$:properties:reg: {'maxItems': 1, 'items':
> [{'minimum': 0, 'maximum': 2}]} should not be valid under {'required':
> ['maxItems']}
> 	hint: "maxItems" is not needed with an "items" list
> 	from schema $id: http://devicetree.org/meta-schemas/items.yaml#
> /home/thomas/linux/Documentation/devicetree/bindings/iio/adc/sophgo,cv1800b-saradc.yaml:
> patternProperties:^channel@[0-2]+$:properties:reg: 'anyOf' conditional
> failed, one must be fixed:
> 	'items' is not one of ['maxItems', 'description', 'deprecated']
> 		hint: Only "maxItems" is required for a single entry if there are no
> constraints defined for the values.
> 	'maxItems' is not one of ['description', 'deprecated', 'const', 'enum',
> 'minimum', 'maximum', 'multipleOf', 'default', '$ref', 'oneOf']
> 	'items' is not one of ['description', 'deprecated', 'const', 'enum',
> 'minimum', 'maximum', 'multipleOf', 'default', '$ref', 'oneOf']
> 	1 is less than the minimum of 2
> 		hint: Arrays must be described with a combination of
> minItems/maxItems/items
> 	hint: cell array properties must define how many entries and what the
> entries are when there is more than one entry.
> 	from schema $id: http://devicetree.org/meta-schemas/core.yaml#
> 
> Isn't it okay to just use minimum and maximum and rely on
> address-cells/size-cells for the number of items allowed ?
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]