diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 8a185250ae5a..23eead3cf77c 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3325,13 +3325,14 @@ static int __init init_dmars(void)
 	iommu_identity_mapping |= IDENTMAP_GFX;
 #endif
 
+	check_tylersburg_isoch();
+
 	if (iommu_identity_mapping) {
 		ret = si_domain_init(hw_pass_through);
 		if (ret)
 			goto free_iommu;
 	}
 
-	check_tylersburg_isoch();
 
 	/*
 	 * If we copied translations from a previous kernel in the kdump