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iommu/arm-smmu: Don't allocate resources for bypass domains 

Until we get fully plumbed into of_iommu_configure, our default
IOMMU_DOMAIN_DMA domains just bypass translation. Since we achieve that
by leaving the stream table entries set to bypass instead of pointing at
a translation context, the context bank we allocate for the domain is
completely wasted. Context banks are typically a rather limited
resource, so don't hog ones we don't need.

Reported-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2016-04-20 14:53:33 +01:00 committed by Joerg Roedel
parent 5f634956cc
commit 9800699c64
1 changed files with 7 additions and 1 deletions
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8
drivers/iommu/arm-smmu.c
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@ -826,6 +826,12 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
if (smmu_domain->smmu)
goto out_unlock;
/* We're bypassing these SIDs, so don't allocate an actual context */
if (domain->type == IOMMU_DOMAIN_DMA) {
smmu_domain->smmu = smmu;
goto out_unlock;
}
/*
* Mapping the requested stage onto what we support is surprisingly
* complicated, mainly because the spec allows S1+S2 SMMUs without
@ -948,7 +954,7 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain)
void __iomem *cb_base;
int irq;
if (!smmu)
if (!smmu || domain->type == IOMMU_DOMAIN_DMA)
return;
/*