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

Prakash Gupta
2025-07-10T18:18:55Z

On 7/5/2025 4:14 AM, Bryan O'Donoghue wrote:
> On 04/07/2025 17:45, Dmitry Baryshkov wrote:
>> What about instead:
>>
>> - keep IOMMU entries as is
> ack
>
>> - Add iommu-maps, mapping the non-pixel SID
>> - In future expand iommu-maps, describing the secure contexts?
>
> Interesting, we are _adding_ so that's not an ABI break and if I'm
> reading the documentation right, there's no hard rule on what iommu-map
> defines i.e. nothing to preclude us from encoding the information we
> want here.
>
> This might work.
>
> drivers/pci/controller/dwc/pcie-qcom.c::qcom_pcie_config_sid_1_9_0()
>
> You can register your platform device to the SID map you parse.

I see few limitations with using iommu-map here, some of these are
listed in [1]

1. We can't specify SMR mask with iommu-map.
2. We can't specify different iommu-addresses range for specific contexts.
3. The secure CB support [2] would require vmid information associated
with per context. I think this can't be provided with iommu-map.

[1]
https://lore.kernel.org/all/85137a8e-45be-3bb2-d094-79754fa2a8be@quicinc.com/
[2]
https://lore.kernel.org/all/20231101071144.16309-2-quic_gkohli@quicinc.com/

Thanks,
Prakash