Revert "arm64: acpi/pci: invoke _DSM whether to preserve firmware PCI setup"

This reverts commit 0a74aec.

Author: ozbenh

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);

include/linux/pci-acpi.h

@@ -107,10 +107,9 @@ 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
+#define DEVICE_LABEL_DSM	0x07
+#define RESET_DELAY_DSM		0x08
+#define FUNCTION_DELAY_DSM	0x09
 
 #else	/* CONFIG_ACPI */
 static inline void acpi_pci_add_bus(struct pci_bus *bus) { }