On 9/16/21 12:53 PM, Oskar Senft wrote:

quoted

Ah, using the node name as indication for both sensor type and
index ? SGTM, though we'd really need input from Rob.
I guess one could also consider something more generic like
"temperature-sensor@0", "voltage-sensor@0", and so on (instead
of [mis-]using reg and a sensor-type field).

Hmm, in that case, maybe we should just remove the "sensors" section.

i2c {
     #address-cells = <1>;
     #size-cells = <0>;

     nct7802@28 {
         compatible = "nuvoton,nct7802";
         reg = <0x28>;
         #address-cells = <1>;
         #size-cells = <0>;

         temperature-sensor@0 { /* LTD */
             status = "okay";
             label = "my local temperature";
         };

         temperature-sensor@1 { /* RTD1 */
             status = "okay";
             mode = <0x2>; /* 3904 transistor */
             label = "other temperature";
         };

         temperature-sensor@3 { */ RTD3 */
             status = "okay";
             mode = <0x3>; /* thermal diode */
             label = "3rd temperature";
        };
    };
};

I think there was a reason for "sensors", because there can be other
bindings on the same level. Documentation/devicetree/bindings/hwmon/ltc2978.txt
lists "regulators", for example.

Where did you find the "sensors" example for ltc2978 ? I don't see it
in the upstream kernel. Or was that derived from the official "regulators"
bindings ?

Now, with "sensors" removed and everything at "top-level", we'll need
to decide what to do if individual sensors are missing. I guess in
that case I would just leave the affected sensors alone, i.e. neither
configure nor disable them and instead read their status from HW. That
way prior uses of the nct7802 in device trees will continue to behave
as before as does the EEPROM-style configuration.

I would like to focus on the implementation of the temperature-sensor
entries for now (i.e. LTD, RTD1, RTD2, RTD3). Support for other sensor
types could be added in a separate change. Would that be acceptable?

Yes, let's do that. I'd like us to keep the "sensors" subnode to have a clear
association and differentiator to other sub-nodes such as "regulators".
Open is if we can use "temperature-sensor@0" or if it would have to be
a chip specific "ltd", but I think we can sort that out after suggesting
an initial set of bindings to Rob.

Thanks,
Guenter