From: Will Deacon <will@kernel.org>
Date: Wed, 21 Aug 2019 18:41:27 +0100
Subject: Revert "iommu/arm-smmu-v3: Disable detection of ATS and PRI"
Git-commit: a91bcc2b65370e7debf1fc26b93a4c2a54433220
Patch-mainline: v5.4-rc1
References: bsc#1175713

This reverts commit b5e86196b83fd68e065a7c811ab8925fb0dc3893.

Now that ATC invalidation is performed in the correct places and without
incurring a locking overhead for non-ATS systems, we can re-enable the
corresponding SMMU feature detection.

Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/arm-smmu-v3.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 0e43529d55fe..b8049ea2e455 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -3336,13 +3336,11 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 	}
 
 	/* Boolean feature flags */
-#if 0	/* ATS invalidation is slow and broken */
 	if (IS_ENABLED(CONFIG_PCI_PRI) && reg & IDR0_PRI)
 		smmu->features |= ARM_SMMU_FEAT_PRI;
 
 	if (IS_ENABLED(CONFIG_PCI_ATS) && reg & IDR0_ATS)
 		smmu->features |= ARM_SMMU_FEAT_ATS;
-#endif
 
 	if (reg & IDR0_SEV)
 		smmu->features |= ARM_SMMU_FEAT_SEV;