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| author | Robin Murphy <robin.murphy@arm.com> | 2016-04-13 20:12:59 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-05-03 20:23:02 +0300 |
| commit | f0cfffc48cac516e37711786227f6808491913a5 (patch) | |
| tree | 889f2264c6e081e8778db9396b5a7c6adc4ebf37 /drivers | |
| parent | e086d912d4d78781652669618e7fb01a4d466703 (diff) | |
| download | linux-f0cfffc48cac516e37711786227f6808491913a5.tar.xz | |
iommu/arm-smmu: Work around MMU-500 prefetch errata
MMU-500 erratum #841119 is tickled by a particular set of circumstances
interacting with the next-page prefetcher. Since said prefetcher is
quite dumb and actually detrimental to performance in some cases (by
causing unwanted TLB evictions for non-sequential access patterns), we
lose very little by turning it off, and what we gain is a guarantee that
the erratum is never hit.
As a bonus, the same workaround will also prevent erratum #826419 once
v7 short descriptor support is implemented.
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/iommu/arm-smmu.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index d8bc20a0efb9..085fc8d808a5 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -203,6 +203,7 @@ #define ARM_SMMU_CB(smmu, n) ((n) * (1 << (smmu)->pgshift)) #define ARM_SMMU_CB_SCTLR 0x0 +#define ARM_SMMU_CB_ACTLR 0x4 #define ARM_SMMU_CB_RESUME 0x8 #define ARM_SMMU_CB_TTBCR2 0x10 #define ARM_SMMU_CB_TTBR0 0x20 @@ -234,6 +235,8 @@ #define SCTLR_M (1 << 0) #define SCTLR_EAE_SBOP (SCTLR_AFE | SCTLR_TRE) +#define ARM_MMU500_ACTLR_CPRE (1 << 1) + #define CB_PAR_F (1 << 0) #define ATSR_ACTIVE (1 << 0) @@ -280,6 +283,7 @@ enum arm_smmu_arch_version { enum arm_smmu_implementation { GENERIC_SMMU, + ARM_MMU500, CAVIUM_SMMUV2, }; @@ -1517,6 +1521,15 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu) cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, i); writel_relaxed(0, cb_base + ARM_SMMU_CB_SCTLR); writel_relaxed(FSR_FAULT, cb_base + ARM_SMMU_CB_FSR); + /* + * Disable MMU-500's not-particularly-beneficial next-page + * prefetcher for the sake of errata #841119 and #826419. + */ + if (smmu->model == ARM_MMU500) { + reg = readl_relaxed(cb_base + ARM_SMMU_CB_ACTLR); + reg &= ~ARM_MMU500_ACTLR_CPRE; + writel_relaxed(reg, cb_base + ARM_SMMU_CB_ACTLR); + } } /* Invalidate the TLB, just in case */ @@ -1762,6 +1775,7 @@ static struct arm_smmu_match_data name = { .version = ver, .model = imp } ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU); ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU); +ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500); ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2); static const struct of_device_id arm_smmu_of_match[] = { @@ -1769,7 +1783,7 @@ static const struct of_device_id arm_smmu_of_match[] = { { .compatible = "arm,smmu-v2", .data = &smmu_generic_v2 }, { .compatible = "arm,mmu-400", .data = &smmu_generic_v1 }, { .compatible = "arm,mmu-401", .data = &smmu_generic_v1 }, - { .compatible = "arm,mmu-500", .data = &smmu_generic_v2 }, + { .compatible = "arm,mmu-500", .data = &arm_mmu500 }, { .compatible = "cavium,smmu-v2", .data = &cavium_smmuv2 }, { }, }; |