Messages in this thread | | | Date | Thu, 17 Aug 2023 17:35:34 +0100 | Subject | Re: [PATCH] iommu/arm-smmu-v3: Simplify stage selection logic | From | Robin Murphy <> |
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On 2023-08-17 17:03, Michael Shavit wrote: > It is invalid for an arm-smmu-v3 to have neither FEAT_TRANS_S1 nor > FEAT_TRANS_S2 bits set, and this is even checked in the probe. > > Only set ARM_SMMU_DOMAIN_S2 if FEAT_TRANS_S1 isn't supported, otherwise set > ARM_SMMU_DOMAIN_S1. This is clearer as the existing code implies that > something more sophisticated is going on with the stage selection logic.
The reason it's like this is because of arm_smmu_enable_nesting(), which *is* the additional thing that's going on with the stage selection logic.
Thanks, Robin.
> Signed-off-by: Michael Shavit <mshavit@google.com> > --- > > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 9b0dc35056019..e74c8c630adfa 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -2206,7 +2206,7 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain, > /* Restrict the stage to what we can actually support */ > if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1)) > smmu_domain->stage = ARM_SMMU_DOMAIN_S2; > - if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2)) > + else > smmu_domain->stage = ARM_SMMU_DOMAIN_S1; > > switch (smmu_domain->stage) { > > base-commit: 6eaae198076080886b9e7d57f4ae06fa782f90ef
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