Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 04/04/2023 09:10, Alexandre Belloni wrote:
>>
>>> +      RTC can be used as a clock source through its clock output pin when
>>> +      supplied.
>>> +    const: 0
>>> +
>>> +  clocks:
>>> +    description: |
>>
>> Do not need '|'.
>>
>>> +      RTC uses this clock for clock input when supplied. Clock has to provide
>>> +      one of these four frequencies: 1Hz, 50Hz, 60Hz or 32.768kHz.
>>> +    maxItems: 1
>>> +
>>> +  aux-voltage-chargeable:
>>> +    enum: [0, 1, 2]
>>> +    description: |
>>> +      Enables trickle charger.
>>> +      0: Charger is disabled (default)
>>> +      1: Charger is enabled
>>> +      2: Charger is enabled with a diode
>>
>> 2 is not an allowed value. I asked to drop this property. It is coming
>> from rtc.yaml. I also do not understand "with a diode". So otherwise it
>> is charging with, I don't know, FET?
> 
> No, what is not explained here (and maybe not unsterstood by the
> submitter) is that the RTC has an extra diode so, 

Value of 2 is still not allowed and if the patch was tested, it would be
clearly visible. Unfortunately patch was not tested...

> charging will always
> enable a diode, select a resistor and then have or not an extra diode.
> Figure2 of the MAX31329 datasheet is great.

So the diode is in the max313xx? Then why enabling it is a property of
DT? Either this should be inferred from compatible or is even a policy,
not a DT property. Just because device has a register for something, is
not an argument that "something" should be in DT.


Best regards,
Krzysztof