diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index f003b3a..d96d45d 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1638,6 +1638,17 @@
 	return 0;
 }
 
+static void arm_smmu_detach_dev(struct device *dev)
+{
+	struct arm_smmu_group *smmu_group = arm_smmu_group_get(dev);
+
+	smmu_group->ste.bypass = true;
+	if (IS_ERR_VALUE(arm_smmu_install_ste_for_group(smmu_group)))
+		dev_warn(dev, "failed to install bypass STE\n");
+
+	smmu_group->domain = NULL;
+}
+
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -1650,7 +1661,7 @@
 
 	/* Already attached to a different domain? */
 	if (smmu_group->domain && smmu_group->domain != smmu_domain)
-		return -EEXIST;
+		arm_smmu_detach_dev(dev);
 
 	smmu = smmu_group->smmu;
 	mutex_lock(&smmu_domain->init_mutex);
@@ -1687,25 +1698,6 @@
 	return ret;
 }
 
-static void arm_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
-{
-	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-	struct arm_smmu_group *smmu_group = arm_smmu_group_get(dev);
-
-	BUG_ON(!smmu_domain);
-	BUG_ON(!smmu_group);
-
-	mutex_lock(&smmu_domain->init_mutex);
-	BUG_ON(smmu_group->domain != smmu_domain);
-
-	smmu_group->ste.bypass = true;
-	if (IS_ERR_VALUE(arm_smmu_install_ste_for_group(smmu_group)))
-		dev_warn(dev, "failed to install bypass STE\n");
-
-	smmu_group->domain = NULL;
-	mutex_unlock(&smmu_domain->init_mutex);
-}
-
 static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
 			phys_addr_t paddr, size_t size, int prot)
 {
@@ -1943,7 +1935,6 @@
 	.domain_alloc		= arm_smmu_domain_alloc,
 	.domain_free		= arm_smmu_domain_free,
 	.attach_dev		= arm_smmu_attach_dev,
-	.detach_dev		= arm_smmu_detach_dev,
 	.map			= arm_smmu_map,
 	.unmap			= arm_smmu_unmap,
 	.iova_to_phys		= arm_smmu_iova_to_phys,