Re: [PATCH 04/22] arm64: dts: qcom: hamoa: Reserve low IOVA range for Iris

[Bryan O'Donoghue <bod@kernel.org>]

On 10/08/2026 14:47, Rob Herring wrote:
>>> As per the reserved-memory.yaml schema document, the iommu-addresses
>>> property for IOVA reservation into /reserved-memory is allowed — it's
>>> documented for IOVA carveout reservations:
>>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/ 
>>> schemas/reserved-memory/reserved-memory.yaml#L56
>> I think that is an entirely reasonable reading of the text
>>
>> Quote:
>>
>> "If no "reg" property is specified, the "iommu-addresses" property
>>    defines carveout regions in the IOVA space for the given device. This
>>    can be useful if a certain memory region should not be mapped through
>>    the IOMMU."
>>
>> Which is exactly what this series does. Excludes a specific IOVA range
>> from being allocated for this device.
> But if "iommu-addresses" is the only property of the reserved memory,
> why put this property in reserved-memory rather than directly in the
> device's node? I'm only questioning where is the right place to
> describe a reserved IOVA.
> 
> Rob

Back from the eclipse, sorry for the delayed response.

Ah I get you.

Yes.

I take your point. This is a property of the node itself; the IOVA < 
600MB only matters _if_ the venus or iris nodes are enabled - otherwise 
an IOVA < 600MB is perfectly fine.

So it follows its a property specific to this node not specific to the 
overall system.

Yep, I agree - its a device/node property, not a top-level property.

---
bod