diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 2724c68c48d3fdac64b61036bda11900a853878a..0e2ea1c785427849b68435eb1c188e8b7d65eb64 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -169,7 +169,6 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 	struct acpi_pci_generic_root_info *ri;
 	struct pci_bus *bus, *child;
 	struct acpi_pci_root_ops *root_ops;
-	union acpi_object *obj;
 
 	ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
 	if (!ri)
@@ -195,23 +194,8 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 	if (!bus)
 		return NULL;
 
-	/*
-	 * Invoke the PCI device specific method (_DSM) #5 'Ignore PCI Boot
-	 * Configuration', which tells us whether the firmware wants us to
-	 * preserve the configuration of the PCI resource tree for this root
-	 * bridge.
-	 */
-	obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1,
-				IGNORE_PCI_BOOT_CONFIG_DSM, NULL);
-	if (obj && obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 0) {
-		/* preserve existing resource assignment */
-		pci_bus_claim_resources(bus);
-	} else {
-		/* reconfigure the resource tree from scratch */
-		pci_bus_size_bridges(bus);
-		pci_bus_assign_resources(bus);
-	}
-	ACPI_FREE(obj);
+	pci_bus_size_bridges(bus);
+	pci_bus_assign_resources(bus);
 
 	list_for_each_entry(child, &bus->children, node)
 		pcie_bus_configure_settings(child);
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index cbaecde2977e311bb17b7603142eabe95f523568..8082b612f5612edb0e10b3b54cb8cc9d30306a27 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -107,7 +107,6 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { }
 #endif
 
 extern const guid_t pci_acpi_dsm_guid;
-#define IGNORE_PCI_BOOT_CONFIG_DSM	0x05
 #define DEVICE_LABEL_DSM	0x07
 #define RESET_DELAY_DSM		0x08
 #define FUNCTION_DELAY_DSM	0x09