diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 9e393b9c5091..30ac0ba55864 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -898,7 +898,8 @@ int __init detect_intel_iommu(void)
 	if (!ret)
 		ret = dmar_walk_dmar_table((struct acpi_table_dmar *)dmar_tbl,
 					   &validate_drhd_cb);
-	if (!ret && !no_iommu && !iommu_detected && !dmar_disabled) {
+	if (!ret && !no_iommu && !iommu_detected &&
+	    (!dmar_disabled || dmar_platform_optin())) {
 		iommu_detected = 1;
 		/* Make sure ACS will be enabled */
 		pci_request_acs();