Re: [PATCH] iommu/arm-smmu-qcom: Enable use of all SMR groups when running bare-metal

[Will Deacon]

On Thu, 21 Aug 2025 10:33:53 +0200, Stephan Gerhold wrote:
> Some platforms (e.g. SC8280XP and X1E) support more than 128 stream
> matching groups. This is more than what is defined as maximum by the ARM
> SMMU architecture specification. Commit 122611347326 ("iommu/arm-smmu-qcom:
> Limit the SMR groups to 128") disabled use of the additional groups because
> they don't exhibit the same behavior as the architecture supported ones.
> 
> It seems like this is just another quirk of the hypervisor: When running
> bare-metal without the hypervisor, the additional groups appear to behave
> just like all others. The boot firmware uses some of the additional groups,
> so ignoring them in this situation leads to stream match conflicts whenever
> we allocate a new SMR group for the same SID.
> 
> [...]

Applied to iommu (arm/smmu/updates), thanks!

[1/1] iommu/arm-smmu-qcom: Enable use of all SMR groups when running bare-metal
      https://git.kernel.org/iommu/c/5583a55e074b

I chatted off-list with Robin about this and we agreed that it's the best
approach for now.

Cheers,
-- 
Will

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