Commit 9800699c authored Apr 20, 2016 by Robin Murphy Committed by Joerg Roedel Apr 21, 2016

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>

parent 5f634956

drivers/iommu/arm-smmu.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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;

		/*