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iommu/arm-smmu: Clarify MMU-500 CPRE workaround

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CPRE workarounds are implicated in at least 5 MMU-500 errata, some of
which remain unfixed. The comment and warning message have proven to be
unhelpfully misleading about this scope, so reword them to get the point
across with less risk of going out of date or confusing users.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/dfa82171b5248ad7cf1f25592101a6eec36b8c9a.1728400877.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Robin Murphy
2024-10-08 16:21:17 +01:00
committed by Will Deacon
parent 8cf0b93919
commit 0dfe314cdd
1 changed files with 2 additions and 2 deletions
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drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
+2 -2
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@@ -130,7 +130,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu)
/*
* Disable MMU-500's not-particularly-beneficial next-page
* prefetcher for the sake of errata #841119 and #826419.
* prefetcher for the sake of at least 5 known errata.
*/
for (i = 0; i < smmu->num_context_banks; ++i) {
reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
@@ -138,7 +138,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu)
arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg);
reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
if (reg & ARM_MMU500_ACTLR_CPRE)
dev_warn_once(smmu->dev, "Failed to disable prefetcher [errata #841119 and #826419], check ACR.CACHE_LOCK\n");
dev_warn_once(smmu->dev, "Failed to disable prefetcher for errata workarounds, check SACR.CACHE_LOCK\n");
}
return 0;