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

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across with less risk of going out of date or confusing users.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 <[email protected]>
Link: https://lore.kernel.org/r/dfa82171b5248ad7cf1f25592101a6eec36b8c9a.1728400877.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <[email protected]>

Author: rmurphy-arm

drivers/iommu/arm/arm-smmu/arm-smmu-impl.c

@@ -130,15 +130,15 @@ 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);
 		reg &= ~ARM_MMU500_ACTLR_CPRE;
 		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;