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

From: Vikash Garodia

Date: Sat Aug 08 2026 - 11:49:56 EST



On 8/7/2026 6:48 PM, Bryan O'Donoghue wrote:
On 07/08/2026 11:22, Vikash Garodia wrote:
I don't like the idea of this series, because it_again_ doesn't tell us
the truth about the hardware. This typicall ends up with bigger problems
honestly...thats all the info i have about the vpu hardware that it
restricts non pixel to DMA from the 0-600MB range. The same i have been
trying for a year now
You are not honest here. You also know that there are secure streams,
which have to use their own IOMMU SIDs. And some of them, as far as I
remember, also have memory range restrictions.
please read the commit description again, the answer is there.

So I don't necessarily get all of the detail out of the commit log myself.

Could you give some detail to address Dmitry's point.

The question as I read it is - are all of the other potential SIDs covered by this change ?


I get the query as "secure streams also have their dedicated reserve regions, so how does this approach helps" - This patch does not reserve any IOVA for secure streams, only the forward looking subnode can assign specific reserve for specific streams.
The patch enforces a common IOVA across all streams, and is good enough to fix the problem we have w.r.t device reset.

So, if we land these patches, how do extend it later to account for all
of that?

forward looking design would be subnode, which we can land ontop of this
series.

Yes it should be possible to branch to make subnodes work on-top of this - accepting that once this lands it becomes ABI and support for this method must be sustained, even after sub-nodes land.


Thats the plan. This goes as ABI with subnode to land on top of it.

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bod