From: Robin Murphy Date: Wed, 20 Apr 2016 13:53:33 +0000 (+0100) Subject: iommu/arm-smmu: Don't allocate resources for bypass domains X-Git-Tag: v4.6-rc5~14^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=9800699c645952da6a7399194d3e762b84cde3cd;p=linux.git 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 Tested-by: Eric Auger Signed-off-by: Robin Murphy Signed-off-by: Will Deacon Signed-off-by: Joerg Roedel --- diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index 5158febd889d..7c39ac4b9c53 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -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; /*