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

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Message-ID: <89aabfbe-79bf-4da7-be44-b6cbd92b72a9@bootlin.com>
Date: Tue, 20 Aug 2024 18:21:07 +0200
From: Thomas Bonnefille <thomas.bonnefille@...tlin.com>
To: Conor Dooley <conor@...nel.org>
Cc: Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen
 <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Chen Wang <unicorn_wang@...look.com>,
 Inochi Amaoto <inochiama@...look.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Miquèl Raynal <miquel.raynal@...tlin.com>,
 linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v4 1/3] dt-bindings: iio: adc: sophgo,cv18xx-saradc.yaml:
 Add Sophgo CV18XX SARADC binding

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@...tlin.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@...tlin.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.
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 ?