Re: [PATCH 1/3] dt-bindings: rtc: Add sii,wakealarm-output-pin property for S35390A

[Krzysztof Kozlowski <krzk@kernel.org>]

On 01/07/2026 19:08, Markus Probst wrote:
> On Wed, 2026-07-01 at 18:48 +0200, Alexandre Belloni wrote:
>> On 01/07/2026 16:43:07+0000, Markus Probst wrote:
>>> On Wed, 2026-07-01 at 17:14 +0200, Krzysztof Kozlowski wrote:
>>>> On 01/07/2026 15:25, Markus Probst wrote:
>>>>>>> +
>>>>>>> +maintainers:
>>>>>>> +  - Alexandre Belloni <alexandre.belloni@bootlin.com>
>>>>>>
>>>>>> This should be someone caring about this hardware.
>>>>> He does have the majority of commits on this driver (excluding merge
>>>>> commits and commits not exclusive to this driver), although most of
>>>>> them are pretty tiny.
>>>>>
>>>>> Who would you suggest instead?
>>>>
>>>> Someone adding features for this driver, maybe driver maintainers. But
>>>> if Alexandre is fine, you can leave him.
>>>>
>>>>>>
>>>>>>> +
>>>>>>> +description:
>>>>>>> +  The S-35390A is a CMOS 2-wire real-time clock IC which operates with the
>>>>>>> +  very low current consumption in the wide range of operation voltage.
>>>>>>> +
>>>>>>> +allOf:
>>>>>>> +  - $ref: rtc.yaml#
>>>>>>> +
>>>>>>> +properties:
>>>>>>> +  compatible:
>>>>>>> +    const: sii,s35390a
>>>>>>> +
>>>>>>> +  reg:
>>>>>>> +    maxItems: 1
>>>>>>> +
>>>>>>> +  sii,wakealarm-output-pin:
>>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>>>> +    enum: [1, 2]
>>>>>>> +    description: |
>>>>>>> +      The output pin to wake up the system.
>>>>>>> +      Default will use the output pin for interrupt signal 2.
>>>>>>> +        <S35390A_OUTPUT_PIN_INT1> : Output pin for interrupt signal 1
>>>>>>> +        <S35390A_OUTPUT_PIN_INT2> : Output pin for interrupt signal 2
>>>>>>
>>>>>> Does that mean device generates the interrupts?
>>>>> Yes.
>>>>>
>>>>
>>>>
>>>> Then I think you miss interrupts property.
>>> From what I can tell the line is used to generate a system wakeup
>>> event.
>>>
>>> There would be no obvious benefit of connecting it to an interrupt
>>> controller, so this property would be obsolete?
>>>
>>
>> Then you need proper wakeup-source support
> Wouldn't that break existing devicetrees?

How?

> 
> The current driver allows to wake up the system, even without
> having wakeup-source set.

Anyway, wakeup-source is already there in rtc, so this would be done. I
don't get though, why there is no benefit of routing it to interrupt
controller (interrupt controllers do wake up the system). Additionally,
if you do not connect it to any interrupt, then how does it wake up the
system?

Best regards,
Krzysztof