RE: [PATCH 1/2] dt-bindings: iio: temperature: Add ADT7604 support to adi,ltc2983

[Stan, Liviu]

Thanks for the comments, here are my answers:

On 28 Apr 2026, Jonathan Cameron wrote:
> I don't know much about these temp sensors, but how is this different
> in practice from a 2-wire RTD?  Obviously one is copper and the other
> probably much more precise platinum but does that matter to us?

The main practical differences are:

- The primary output is IIO_RESISTANCE, read from the resistance result
   bank (0x0060-0x00AF). This bank is marked as reserved for the other 
   devices
- Sensor configuration bits 21:18 are hardcoded to 0b1001 for all
   copper trace configurations. For the sub-ohm variant, bits 17:0 are 
   also zeroed; a >1Ω trace will have the excitation current and an 
   optional custom table in those bits. For the existing custom RTD and
   thermistor types, the custom table is required by the binding. For
   copper trace, it is optional (and forbidden for the sub-ohm variant).
   And for leak detector as well it is optional.
- When a custom table is present, a second IIO_TEMP channel also
   appears, reading from the temperature bank. Same dual-output
   behavior for leak detector.

That said, the hardware uses the same custom RTD mode (sensor
type 18) internally.

> I'd go with "LTC2983 and similar" for the title now as it's
> to long. Leave the description to list amount more info.
>
> Alphabetical order and it might be worth thinking about switching this
> to a bulleted list with one device per line as it'll make adding new ones
> neater. (obviously they are already not in numeric order, so fix that too ;)

Will do.

> Is the absences of them enough to indicate this mode?  I.e. are there other
> modes
> with no specified excitation mode or custom rtd table?
> 
> I'm trying to work out if we can map this to the existing binding for
> custom rtd just be adding more constraints + making existing ones more
> specific.
> 
> I don't mind if we can't and have to add a new child node definition but
> I'm not yet sure that's the case.

You're right that the absence of both properties could imply sub-ohm mode, 
so I think we could drop the boolean. But the issue with reusing rtd@ is that 
adi,custom-rtd is currently required for sensor-type 18, and several 
RTD-specific properties (adi,number-of-wires, adi,rtd-curve,
adi,rsense-share) have no meaning for copper trace and would need to be 
forbidden (they could also be ignored in the driver). In my opinion, separate 
nodes for both copper trace and leak detectors would make sense, but I'm 
happy to go whichever way you prefer.

> I'd avoid describing things as xx only as that tends to become wrong fast!
> Better to put that as a conditional only (as you have below)
> Maybe here you can say, (some parts only) or something like that.

Will switch to "some parts only". 

Thanks,
Liviu