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

Dmitry Baryshkov
2025-10-07T19:40:41Z

On Tue, 7 Oct 2025 at 17:44, Bryan O'Donoghue <bod@kernel.org> wrote:
>
> On 07/10/2025 15:29, Bryan O'Donoghue wrote:
> > On 07/10/2025 15:25, Bryan O'Donoghue wrote:
> >> 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.
> >
> > i.e. you can keep the FUNCTION_ID "metadata" in the driver and associate
> > specific iommu indexes with the FUNCTION_ID you want in there.
> >
> > That way you could have multiple FUNCTION_ID smmu entries in the DT and
> > just associate the DT indexes locally in drivers/platform/qcom/
> > iris_metadata_goes_here.c
> >
> > ---
> > bod
>
> Actually why can't we specify FUNCTION_ID in the iommus = <entries>
>
> Surely we could do
>
> #iommu-cells = <4>;

Because #iommu-cells is a part of the apps_smmu: device rather than a
part ofthe iris/venus/GPU/display/etc.

> iommus = <&apps_smmu 0x420 0x2 FUNCTION_ID>;
>
> and encode the real data we need directly in the iommus list...
>
> ---
> bod

--
With best wishes
Dmitry