Re: [PATCH 1/4] dt-bindings: iio: adc: add ti,ads122c14

[David Lechner]

On 6/22/26 4:55 AM, Jonathan Cameron wrote:
> On Sun, 21 Jun 2026 16:14:57 -0500
> David Lechner <dlechner@xxxxxxxxxxxx> wrote:
> 
>> On 6/21/26 1:41 PM, Jonathan Cameron wrote:
>>> On Mon, 15 Jun 2026 16:59:59 -0500
>>> "David Lechner (TI)" <dlechner@xxxxxxxxxxxx> wrote:
>>>   

...

>>>> +        description: The current output of the excitation channels in microamps.
>>>> +        minimum: 1
>>>> +        maximum: 1000
>>>> +
>>>> +      current-chopping:
>>>> +        $ref: /schemas/types.yaml#/definitions/flag
>>>> +        description:
>>>> +          If provided, the two excitation channels are to be used with current
>>>> +          chopping enabled.  
>>>
>>> Can I have a reference for that? My initial read suggests it's the input channels  
>>
>> No. :-)
>>
>> I must have got two ideas mixed together in my head to come up with
>> this. Clearly this should be `input-channel-rotation` or something like
>> that (we discussed in another thread already). Also curious if you thing
>> any of these properties are common enough to promote to adc.yaml or if we
>> should just make them e.g. `ti,input-channel-rotation` (you might not have
>> had time to read the threads on that yet).
> 
> It's turned up in a couple of drivers and the concept is fairly standard I think
> so I'm fine with promoting this to a top level property if the definition can
> be generic enough.
> 
> For a non TI example, the LTC2893 has this as well for it's thermistor settings.
> It might be worth comparing the approach given here with what we have there.
> In that case there are specific node types for different types of things that
> are wired up with constraints on things like excitation currents.
> It kind of constrains things to the sane known use cases.  However that is
> partly because that device does (I think) more type specific handling than
> we have here.

LTC2983 has current source rotation, so it has a adi,current-rotate property
which would be the same as the excitation-current-rotation property that
we have proposed here (named current-chopping in the patch, but better name
was suggested in later discussion).

So not quite the same as the input-rotation property that we would need for
this chip. Although ti,ads1262 that Kurt is working on will have both.

> 
>>
>>> that are chopped.  For GC_EN
>>> "When enabled, the device automatically swaps
>>> the analog inputs and takes the average of two consecutive conversions to
>>> cancel the internal offset voltage"
>>>
>>>