Re: [PATCH v2 1/2] dt-bindings: iio: adc: Add TI ADS1120 binding

[David Lechner <dlechner@baylibre.com>]

On 11/15/25 12:31 PM, Jonathan Cameron wrote:
> On Sun,  9 Nov 2025 19:41:18 +0530
> Ajith Anandhan <ajithanandhan0406@gmail.com> wrote:
> 
>> Add device tree binding documentation for the Texas Instruments
>> ADS1120.
>>
>> The binding defines required properties like compatible, reg, and
>> SPI configuration parameters.
>>
>> Signed-off-by: Ajith Anandhan <ajithanandhan0406@gmail.com>
>> ---
>>  .../bindings/iio/adc/ti,ads1120.yaml          | 109 ++++++++++++++++++
>>  1 file changed, 109 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
>> new file mode 100644
>> index 000000000..2449094af
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
>>
>> +
>> +  vref-supply:
>> +    description: |
>> +      Optional external voltage reference. Can be connected to either
>> +      REFP0/REFN0 or REFP1/REFN1 pins. If not supplied, the internal
>> +      2.048V reference is used.
> 
> How do you know which set of inputs is used?  Looks like a register
> needs to be programmed to pick between them.

I would just make two supply properties for this, ref0-supply and ref1-supply

> 
>> +
>> +  ti,avdd-is-ref:
>> +    type: boolean
>> +    description: |
>> +      If present, indicates that the AVDD supply voltage is of sufficient
>> +      quality and stability to be used as the voltage reference instead of
>> +      the internal reference. This allows the driver to select AVDD as the
>> +      reference source for potentially better performance.
> 
> This one is interesting as I don't recall anyone arguing this made
> sense before.  In what way better performance?  Are their boards out
> there where this definitely makes sense to do?
> 

Seems harmless to have the property even if no one ever uses it. But I would
be curious to know the answers to those questions too.