Re: [PATCH v3 1/9] dt-bindings: misc: Describe TI FPC202 dual port controller

Romain Gantois
2024-11-27T08:20:35Z

On mardi 26 novembre 2024 19:09:43 heure normale d’Europe centrale Conor Dooley wrote:
> On Tue, Nov 26, 2024 at 09:05:42AM +0100, Romain Gantois wrote:
> > Hello Conor,
...
> >
> > But then again, you could consider that DT bindings should only describe
> > what is possible, and not only what makes sense as a use case. I don't
> > really know how to answer this question myself, so I'll refer to the
> > maintainers' opinions.
> I don't really know what how this device works, which is why I am asking
> questions. If there is no use case were someone would only wire up one
> of the downstream ports then making both required is fine. I was just
> thinking that someone might only hook devices up to one side of it and
> leave the other unused entirely. Seemed like it could serve its role
> without both sides being used based on the diagram in
> https://docs.kernel.org/i2c/i2c-address-translators.html
> unless it is not possible for the atr to share the "parent" i2c bus with
> other devices?

It is possible for the FPC202 to share it's parent bus with other devices. And I
guess you could wire up only one port and use the component as a simple
address translator and GPIO aggregator.

So indeed, requiring both ports to be described seems unnecessary.

Thanks,

--
Romain Gantois, Bootlin
Embedded Linux and Kernel engineering