Revert "iommu/arm-smmu: Leave power resources enabled across unmap and sync ops"

This reverts commit fc6d479bac4c756359388647d45f39f08d0c8534. The
functionality offered by this change was not implemented correctly,
so revert it in favor of a different way of addressing the issue
that was supposed to be fixed.

Change-Id: Id061372026dea2960758c4dad0a5e37c2604576e
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>

arch/arm/configs/vendor/sdxlemur.config

@@ -22,7 +22,6 @@ CONFIG_IOMMU_IO_PGTABLE_FAST=y
 CONFIG_QCOM_IOMMU_IO_PGTABLE_QUIRKS=y
 CONFIG_IOMMU_LIMIT_IOVA_ALIGNMENT=y
 CONFIG_ARM_SMMU_SKIP_MAP_POWER_ON=y
-CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP=y
 CONFIG_QTI_IOMMU_SUPPORT=y
 CONFIG_QCOM_SCM=y
 CONFIG_QCOM_SECURE_BUFFER=y

arch/arm64/configs/vendor/holi_QGKI.config

@@ -5,7 +5,6 @@ CONFIG_QCOM_LAZY_MAPPING=y
 CONFIG_DEBUG_FS=y
 CONFIG_IOMMU_DYNAMIC_DOMAINS=y
 CONFIG_ARM_SMMU_SKIP_MAP_POWER_ON=y
-CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP=y
 CONFIG_QCOM_SECURE_BUFFER=y
 # CONFIG_ZONE_DMA32 is not set
 CONFIG_EDAC_KRYO_ARM64=y

arch/arm64/configs/vendor/lahaina_QGKI.config

@@ -13,7 +13,6 @@ CONFIG_ION_MSM_HEAPS=y
 CONFIG_IOMMU_IO_PGTABLE_FAST=y
 CONFIG_IOMMU_DYNAMIC_DOMAINS=y
 CONFIG_ARM_SMMU_SKIP_MAP_POWER_ON=y
-CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP=y
 # CONFIG_IOMMU_IO_PGTABLE_FAST_SELFTEST is not set
 # CONFIG_IOMMU_IO_PGTABLE_FAST_PROVE_TLB is not set
 # CONFIG_SOFTLOCKUP_DETECTOR is not set

drivers/iommu/Kconfig

@@ -548,15 +548,6 @@ config ARM_SMMU_SKIP_MAP_POWER_ON
 
 	  If unsure, say N here.
 
-config ARM_SMMU_POWER_OFF_AFTER_UNMAP
-	bool "Remove power votes after unmapping memory"
-	depends on ARM_SMMU && QGKI
-	help
-	  Support for ensuring that votes for power resources are removed
-	  after memory is unmapped. This should be enabled when it is guaranteed
-	  that there are no outstanding TLB invalidations after the memory
-	  has been unmapped from the IOMMU page tables.
-
 config ARM_SMMU_V3
 	tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
 	depends on ARM64

drivers/iommu/arm-smmu.c

@@ -3257,25 +3257,9 @@ static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
 	spin_lock_irqsave(&smmu_domain->cb_lock, flags);
 	ret = ops->unmap(ops, iova, size, gather);
 	spin_unlock_irqrestore(&smmu_domain->cb_lock, flags);
-	/*
-	 * The votes for power resources can only be removed if there are no
-	 * outstanding TLB invalidation operations. This is true when the
-	 * downstream io-pgtable-arm optimizations are in use, as the code that
-	 * unmaps the memory from the IOMMU page tables ensures that all TLB
-	 * operations are complete before returning.
-	 *
-	 * However, the upstream io-pgtable-arm implementation allows for a TLB
-	 * invalidation to be in progress when control is returned back here,
-	 * and the votes for the power resources will be removed, which has been
-	 * observed to cause problems where unmapping buffers takes a long time.
-	 * For those scenarios, leave the votes for power resources in place,
-	 * and rely on the subsequent sync operation to remove the votes.
-	 */
-#ifdef CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP
 	arm_smmu_rpm_put(smmu);
 
 	arm_smmu_domain_power_off(domain, smmu_domain->smmu);
-#endif
 	/*
 	 * While splitting up block mappings, we might allocate page table
 	 * memory during unmap, so the vmids needs to be assigned to the
@@ -3313,20 +3297,12 @@ static void arm_smmu_iotlb_sync(struct iommu_domain *domain,
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 
 	if (smmu_domain->flush_ops) {
-		/*
-		 * Voting for power resources when
-		 * CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP is enabled, is required
-		 * as the unmap call has removed the votes for the power
-		 * resources.
-		 */
-#ifdef CONFIG_ARM_SMMU_POWER_OFF_AFTER_UNMAP
 		arm_smmu_rpm_get(smmu);
 		if (arm_smmu_domain_power_on(domain, smmu)) {
 			WARN_ON(1);
 			arm_smmu_rpm_put(smmu);
 			return;
 		}
-#endif
 		smmu_domain->flush_ops->tlb_sync(smmu_domain);
 		arm_smmu_domain_power_off(domain, smmu);
 		arm_smmu_rpm_put(smmu);