Re: [PATCH RFC] dt-bindings: thunderbolt: Add Qualcomm USB4 Host Router

[Mika Westerberg]

Hi,

On Thu, Sep 18, 2025 at 11:05:42AM +0200, Konrad Dybcio wrote:
> > I it hard to change these DT bindings later on? If yes then I would
> > definitely think forward and make this support MSI from the get-go.
> 
> dt-bindings (attempt to) promise an ABI-like interface, so bindings
> for *a given IP block* ("dt-bindings describe the hardware") should
> not change, unless there's something critically wrong (e.g. "this
> could have never really worked").

Then I think it is good to think few steps forward and make sure when
Qualcomm adds MSI to their IP it can be easily desribed in the DT bindings.

> Adding new properties is always OK, marking the new properties  as
> 'required' is not (unless it falls into the aforementioned case).
> 
> It's also totally OK to add MSI properties to e.g. Apple Host Router
> bindings specifically when they come around, as it's simply a different
> piece of hardware. It's also OK to create a usb4-host-router.yaml down
> the line, which will act as a common include and perform any
> maintenance/code churn, so long as it doesn't end up in the bindings
> for any specific hw block (e.g. this QC one) becoming more strict
> than they were on HEAD^.

Okay thanks for the explanation.