Re: [PATCH v3 11/11] dt-bindings: hwmon: allow specifying channels for tmp421

[Krzysztof Adamski <krzysztof.adamski@nokia.com>]

Dnia Sat, Oct 02, 2021 at 07:22:19AM -0700, Guenter Roeck napisał(a):
>On Thu, Sep 30, 2021 at 09:19:49AM +0200, Krzysztof Adamski wrote:
>> Add binding description for the per temperature channel configuration
>> like labels and n-factor.
>>
>> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>> ---
>>  .../devicetree/bindings/hwmon/ti,tmp421.yaml  | 66 +++++++++++++++++++
>>  1 file changed, 66 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/ti,tmp421.yaml b/Documentation/devicetree/bindings/hwmon/ti,tmp421.yaml
>> index 47040ace4f73..0d4ea2209500 100644
>> --- a/Documentation/devicetree/bindings/hwmon/ti,tmp421.yaml
>> +++ b/Documentation/devicetree/bindings/hwmon/ti,tmp421.yaml
>> @@ -24,12 +24,49 @@ properties:
>>    reg:
>>      maxItems: 1
>>
>> +  '#address-cells':
>> +    const: 1
>> +
>> +  '#size-cells':
>> +    const: 0
>> +
>>  required:
>>    - compatible
>>    - reg
>>
>>  additionalProperties: false
>>
>> +patternProperties:
>> +  "^input@([0-4])$":
>
>Was there agreement on "input" ? It is a somewhat odd name for a temperature
>sensor. If that name can be used to distinguish child sensor types, it might
>make sense to have a well defined name to state that this is a temperature
>sensor.

Nope, no conclusion on that, yet, thus I did not change that and I was
still using the same approach I had on v1. For me it can be a "channel@X", a
"temperature@X".. whatever you decide.

However I'm in favor of some generic name, like "channel" or "input",
and using some "type property", if required, instead of calling the
nodes "temperatue@X", "voltage@X".

>> +    type: object
>> +    description: |
>> +      Represents channels of the device and their specific configuration.
>> +
>> +    properties:
>> +      reg:
>> +        description: |
>> +          The channel number. 0 is local channel, 1-4 are remote channels
>
>Which of the supported chips has 4 remote channels ?

True, there is no TMP424. I will fix that in v4.

>
>> +        items:
>> +          minimum: 0
>> +          maximum: 4
>> +
>> +      label:
>> +        description: |
>> +          A descriptive name for this channel, like "ambient" or "psu".
>> +
>> +      n-factor:
>
>n-factor or "ti,n-factor" ? The unit is chip specific, after all.

Or ti,nfactor, as used by tmp513? Again, there was no clear conclusion
so I didn't change that. Let me know what is your decision and I will
obey that.

>
>> +        description: |
>> +          The value (two's complement) to be programmed in the channel specific N correction register.
>> +          For remote channels only.
>> +        items:
>> +          minimum: 0
>> +          maximum: 1
>
>Is this the correct value range ? The value range (in integer form) is
>-128 .. 127 (or 0 .. 255 as unsigned), not 0..1.

True, I must have misunderstood this minimum/maximum and confused it
with the number of items or something. Now, since DT does not really
handle signed values and considers everything an unsigned, should I use
0..255 or -128..127?

Krzysztof