Re: [PATCH v2 2/2] gpio: aggregator: add gpio-aggregator DT compatible

[Herve Codina <herve.codina@bootlin.com>]

Hi all,

On Fri, 13 Feb 2026 08:31:21 +0100
Krzysztof Kozlowski <krzk@kernel.org> wrote:

> > 
> > Or is the issue just with the name of the compatible I used being
> > called "gpio-aggregator"?  
> 
> No, the issue is that there is no hardware you are trying represent in DTS.

Except if you have a piece of hardware that invert the gpio line.

In that case you need to set GPIO_ACTIVE_LOW somewhere.

The aggregator allows to describe this line inverter.

Of course, if the gpio is connected to a hardware component handled by the
kernel, the DT node describing this hardware can set the flag.

The issue is for GPIOs that are just GPIOs and should by a user-space
application as GPIOs.

Some bindings exist for GPIO and do not describe the hardware but the
feature. For instance:
https://elixir.bootlin.com/linux/v6.18/source/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
https://elixir.bootlin.com/linux/v6.18/source/Documentation/devicetree/bindings/power/reset/gpio-poweroff.yaml
https://elixir.bootlin.com/linux/v6.18/source/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml

Can we consider the gpio-aggregator describing the wires that should be
grouped together.

Industrial board can have some GPIOs grouped together and used as inputs or
ouputs of this industrial board.

As output they command an external system. As input, they get feedback from
this system.

gpio-aggregator describes those lines.

In that sense, it describes hardware.
Maybe the "gpio-aggregator" name doesn't reflect that and a compatible such as
"gpio-equipment" could make sense.


Best regards,
Hervé