linux-kernel - Re: [PATCH 1/3] dt-bindings: mfd: twl: enable power button also for twl603x

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Message-ID: <beabb9f7-fcf4-4c1d-a259-6c48e82fbcf5@kernel.org>
Date: Tue, 21 Oct 2025 11:58:49 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Andreas Kemnade <andreas@...nade.info>
Cc: akemnade@...nel.org, Lee Jones <lee@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Dmitry Torokhov <dmitry.torokhov@...il.com>, Tony Lindgren
 <tony@...mide.com>, Kevin Hilman <khilman@...nel.org>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-input@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: mfd: twl: enable power button also for
 twl603x

On 21/10/2025 10:45, Andreas Kemnade wrote:
> On Tue, 21 Oct 2025 09:10:28 +0200
> Krzysztof Kozlowski <krzk@...nel.org> wrote:
> 
>> On 20/10/2025 14:31, akemnade@...nel.org wrote:
>>> From: Andreas Kemnade <andreas@...nade.info>
>>>
>>> TWL603x has also a power button, so add the corresponding subnode.  
>>
>> No, we don't add subnodes just because there is a power button. This
>> needs broader explanation, see also my further comment.
>>
> Hmm, what is the general pattern to follow if a mfd device has some
> functionality which depends on some optional external components?

Please describe it better - how these nodes depend on external
component? The power button logic/IC is in this device always. It is not
optional.

> The might be a power button connected to it or not. I find it ugly
> to have non-existent stuff in the system.
> In general, yes I understand the argument against the subnode.
> 
>>>
>>> Signed-off-by: Andreas Kemnade <andreas@...nade.info>
>>> ---
>>>  Documentation/devicetree/bindings/mfd/ti,twl.yaml | 40 ++++++++++++++++++-----
>>>  1 file changed, 32 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mfd/ti,twl.yaml b/Documentation/devicetree/bindings/mfd/ti,twl.yaml
>>> index 776b04e182cb2..3527fee32cb07 100644
>>> --- a/Documentation/devicetree/bindings/mfd/ti,twl.yaml
>>> +++ b/Documentation/devicetree/bindings/mfd/ti,twl.yaml
>>> @@ -55,6 +55,15 @@ allOf:
>>>  
>>>          gpadc: false
>>>  
>>> +        pwrbutton:
>>> +          properties:
>>> +            compatible:
>>> +              const: ti,twl4030-pwrbutton
>>> +            interrupts:
>>> +              items:
>>> +                - items:
>>> +                    const: 8  
>>
>> What is the point of defining const interrupts? If they are const, then
>> it is implied by compatible and defined in the driver.
>>
>> Anyway, double items does not look right here. This is an odd syntax.
>>
> Quoting Rob:
> As 'interrupts' is a matrix, this needs to be:
> 
> interrupts:
>   items:
>     - items:
>         - const: 8
> 
> https://lore.kernel.org/linux-omap/20240318150750.GA4000895-robh@kernel.org/


OK, this answers second part but I don't understand why even having this
in DT. If this is fixed, should be implied by the compatible?


Best regards,
Krzysztof