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

Thomas Bonnefille
2024-08-20T16:21:25Z

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.
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 ?