[PATCH] iommu/arm-smmu: Clarify MMU-500 CPRE workaround

Robin Murphy robin.murphy at arm.com
Fri Sep 13 05:55:38 PDT 2024


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across with less risk of going out of date or confusing users.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 at arm.com>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
index 9dc772f2cbb2..2edb1c1658ad 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
@@ -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 ACR.CACHE_LOCK\n");
 	}
 
 	return 0;
-- 
2.39.2.101.g768bb238c484.dirty




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