Re: [PATCH] dt-bindings: input: gpio-keys: allow generic 'interrupt-parent' for subnodes

[Krzysztof Kozlowski <krzk@kernel.org>]

On 27/09/2024 23:27, Dmitry Torokhov wrote:
> On Fri, Sep 27, 2024 at 10:30:12AM +0200, Krzysztof Kozlowski wrote:
>> On 27/09/2024 10:15, Wolfram Sang wrote:
>>> Allow interrupt-parent in the main node, so it can be inherited to all
>>> subnodes. This is more compact and less error-prone.
>>>
>>> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>>> ---
>>>
>>> It would fix dtbs_check for arch/arm/boot/dts/renesas/r8a7779-marzen.dts
>>> and would simplify arch/arm/boot/dts/renesas/r7s72100-rskrza1.dts.
>>>
>>> Plus, it is the behaviour I would expect.
>>>
>>>  Documentation/devicetree/bindings/input/gpio-keys.yaml | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/input/gpio-keys.yaml b/Documentation/devicetree/bindings/input/gpio-keys.yaml
>>> index cc78c2152921..8fc331e01f7e 100644
>>> --- a/Documentation/devicetree/bindings/input/gpio-keys.yaml
>>> +++ b/Documentation/devicetree/bindings/input/gpio-keys.yaml
>>> @@ -15,6 +15,9 @@ properties:
>>>        - gpio-keys
>>>        - gpio-keys-polled
>>>  
>>> +  interrupt-parent:
>>> +    description: Common interrupt parent for the following subnodes
>>
>> That's a bit against DT spec:
>>
>> "Nodes that represent interrupt-generating devices contain an
>> interrupt-parent property..."
>>
>> but gpio-keys node you marked as interrupt-parent does not generate
>> interrupts, so I do not think this is correct.
> 
> I think this can be read multiple ways. The device here is gpio-keys and
> interrupt-parent would be attached to that node. Children nodes do not
> represent individual devices, they just a convenient abstraction to
> describe the hardware.

Not really. There is no device like "gpio-keys". Each key is a separate,
independent device. They are no grouped, they do no share anything. From
Linux perspective they share, but on hardware - zero common pieces,
independent devices.

And this is reflected in interrupts property. Individual devices
generating interrupts - so each key connected over GPIO - has interrupts
property.

Best regards,
Krzysztof