Re: [PATCH v3 0/5] Introduce "non-pixel" sub node within iris video node

Bryan O'Donoghue
2025-10-07T14:25:34Z

On 07/10/2025 15:11, Charan Teja Kalla wrote:
> a) Keep iommus max items as 2, which is unchanged.
> b) Repeat the same sid for both entries, i.e.,
> iommus = <&apps_smmu 0x1940 0x0000>,
> - <&apps_smmu 0x1947 0x0000>;
> + <&apps_smmu 0x1940 0x0000>;
>
> and then create the new device as a platform device independent of dt.
> RFC for this is posted[1].

If you are going to bury iommu data into the platform code in the
driver, why do you need to modify this array at all ?

The upstream DT should describe what is correct for the APSS - Linux.

There's nothing to stop having an exotic set of platform code in drivers
to setup SMMU entries for non-APSS system agents though.

Seems a shame though - in the ideal the DT should describe the whole
hardware and the FUNCTION_ID would be included into the iommu entries.

Rob suggested using an implicit index for function id

https://lore.kernel.org/all/CAL_JsqK9waZK=i+ov0jV-PonWSfddwHvE94Q+pks4zAEtKc+yg@mail.gmail.com/

Couldn't we list the entire set of iommus - then detach - subsequently
re-attaching in our platform code with FUNCTION_IDs we keep listed in
our drivers ?

That way the DT is complete and correct, we have a compliant upstream DT
but we also find a way to make the FUNCTION_ID specific setup we need.

---
bod