diff --git a/drivers/pci/hotplug/pciehp_acpi.c b/drivers/pci/hotplug/pciehp_acpi.c
index 0cd49b728045..88a5c57f2e5b 100644
--- a/drivers/pci/hotplug/pciehp_acpi.c
+++ b/drivers/pci/hotplug/pciehp_acpi.c
@@ -28,15 +28,18 @@
 
 #define PCIEHP_DETECT_PCIE	(0)
 #define PCIEHP_DETECT_ACPI	(1)
-#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_PCIE
+#define PCIEHP_DETECT_AUTO	(2)
+#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_AUTO
 
 static int slot_detection_mode;
 static char *pciehp_detect_mode;
 module_param(pciehp_detect_mode, charp, 0444);
 MODULE_PARM_DESC(pciehp_detect_mode,
-		 "Slot detection mode: pcie, acpi\n"
-		 "  pcie - Use PCIe based slot detection (default)\n"
-		 "  acpi - Use ACPI for slot detection\n");
+	 "Slot detection mode: pcie, acpi, auto\n"
+	 "  pcie          - Use PCIe based slot detection\n"
+	 "  acpi          - Use ACPI for slot detection\n"
+	 "  auto(default) - Auto select mode. Use acpi option if duplicate\n"
+	 "                  slot ids are found. Otherwise, use pcie option\n");
 
 static int is_ejectable(acpi_handle handle)
 {
@@ -103,12 +106,81 @@ static int __init parse_detect_mode(void)
 		return PCIEHP_DETECT_PCIE;
 	if (!strcmp(pciehp_detect_mode, "acpi"))
 		return PCIEHP_DETECT_ACPI;
+	if (!strcmp(pciehp_detect_mode, "auto"))
+		return PCIEHP_DETECT_AUTO;
 	warn("bad specifier '%s' for pciehp_detect_mode. Use default\n",
 	     pciehp_detect_mode);
 	return PCIEHP_DETECT_DEFAULT;
 }
 
+static struct pcie_port_service_id __initdata port_pci_ids[] = {
+	{
+		.vendor = PCI_ANY_ID,
+		.device = PCI_ANY_ID,
+		.port_type = PCIE_ANY_PORT,
+		.service_type = PCIE_PORT_SERVICE_HP,
+		.driver_data =  0,
+        }, { /* end: all zeroes */ }
+};
+
+static int __initdata dup_slot_id;
+static int __initdata acpi_slot_detected;
+static struct list_head __initdata dummy_slots = LIST_HEAD_INIT(dummy_slots);
+
+/* Dummy driver for dumplicate name detection */
+static int __init dummy_probe(struct pcie_device *dev,
+			      const struct pcie_port_service_id *id)
+{
+	int pos;
+	u32 slot_cap;
+	struct slot *slot, *tmp;
+	struct pci_dev *pdev = dev->port;
+	if (!(slot = kzalloc(sizeof(*slot), GFP_KERNEL)))
+		return -ENOMEM;
+	/* Note: pciehp_detect_mode != PCIEHP_DETECT_ACPI here */
+	if (pciehp_get_hp_hw_control_from_firmware(pdev))
+		return -ENODEV;
+	if (!(pos = pci_find_capability(pdev, PCI_CAP_ID_EXP)))
+		return -ENODEV;
+	pci_read_config_dword(pdev, pos + PCI_EXP_SLTCAP, &slot_cap);
+	slot->number = slot_cap >> 19;
+	list_for_each_entry(tmp, &dummy_slots, slot_list) {
+		if (tmp->number == slot->number)
+			dup_slot_id++;
+	}
+	list_add_tail(&slot->slot_list, &dummy_slots);
+	if (!acpi_slot_detected && pciehp_detect_acpi_slot(pdev->subordinate))
+		acpi_slot_detected = 1;
+	return -ENODEV;         /* dummy driver always returns error */
+}
+
+static struct pcie_port_service_driver __initdata dummy_driver = {
+        .name           = "pciehp_dummy",
+        .id_table       = port_pci_ids,
+        .probe          = dummy_probe,
+};
+
+static int __init select_detection_mode(void)
+{
+	struct slot *slot, *tmp;
+	pcie_port_service_register(&dummy_driver);
+	pcie_port_service_unregister(&dummy_driver);
+	list_for_each_entry_safe(slot, tmp, &dummy_slots, slot_list) {
+		list_del(&slot->slot_list);
+		kfree(slot);
+	}
+	if (acpi_slot_detected && dup_slot_id)
+		return PCIEHP_DETECT_ACPI;
+	return PCIEHP_DETECT_PCIE;
+}
+
 void __init pciehp_acpi_slot_detection_init(void)
 {
 	slot_detection_mode = parse_detect_mode();
+	if (slot_detection_mode != PCIEHP_DETECT_AUTO)
+		goto out;
+	slot_detection_mode = select_detection_mode();
+out:
+	if (slot_detection_mode == PCIEHP_DETECT_ACPI)
+		info("Using ACPI for slot detection.\n");
 }