diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 42a4585dd76da..cfb597751f5ba 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1865,7 +1865,6 @@ static int iommu_get_def_domain_type(struct iommu_group *group,
 static int iommu_get_default_domain_type(struct iommu_group *group,
 					 int target_type)
 {
-	const struct iommu_ops *ops = group_iommu_ops(group);
 	struct device *untrusted = NULL;
 	struct group_device *gdev;
 	int driver_type = 0;
@@ -1876,11 +1875,13 @@ static int iommu_get_default_domain_type(struct iommu_group *group,
 	 * ARM32 drivers supporting CONFIG_ARM_DMA_USE_IOMMU can declare an
 	 * identity_domain and it will automatically become their default
 	 * domain. Later on ARM_DMA_USE_IOMMU will install its UNMANAGED domain.
-	 * Override the selection to IDENTITY if we are sure the driver supports
-	 * it.
+	 * Override the selection to IDENTITY.
 	 */
-	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU) && ops->identity_domain)
+	if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
+		static_assert(!(IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU) &&
+				IS_ENABLED(CONFIG_IOMMU_DMA)));
 		driver_type = IOMMU_DOMAIN_IDENTITY;
+	}
 
 	for_each_group_device(group, gdev) {
 		driver_type = iommu_get_def_domain_type(group, gdev->dev,
@@ -3016,18 +3017,9 @@ static int iommu_setup_default_domain(struct iommu_group *group,
 	if (req_type < 0)
 		return -EINVAL;
 
-	/*
-	 * There are still some drivers which don't support default domains, so
-	 * we ignore the failure and leave group->default_domain NULL.
-	 */
 	dom = iommu_group_alloc_default_domain(group, req_type);
-	if (!dom) {
-		/* Once in default_domain mode we never leave */
-		if (group->default_domain)
-			return -ENODEV;
-		group->default_domain = NULL;
-		return 0;
-	}
+	if (!dom)
+		return -ENODEV;
 
 	if (group->default_domain == dom)
 		return 0;