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

[Bryan O'Donoghue]

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.

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bod