diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4e84fd4..e9651f0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -77,7 +77,7 @@
 unsigned long pci_hotplug_io_size  = DEFAULT_HOTPLUG_IO_SIZE;
 unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
 
-enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_SAFE;
+enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;
 
 /*
  * The default CLS is used if arch didn't set CLS explicitly and not
@@ -3568,10 +3568,14 @@
 				pci_hotplug_io_size = memparse(str + 9, &str);
 			} else if (!strncmp(str, "hpmemsize=", 10)) {
 				pci_hotplug_mem_size = memparse(str + 10, &str);
+			} else if (!strncmp(str, "pcie_bus_tune_off", 17)) {
+				pcie_bus_config = PCIE_BUS_TUNE_OFF;
 			} else if (!strncmp(str, "pcie_bus_safe", 13)) {
 				pcie_bus_config = PCIE_BUS_SAFE;
 			} else if (!strncmp(str, "pcie_bus_perf", 13)) {
 				pcie_bus_config = PCIE_BUS_PERFORMANCE;
+			} else if (!strncmp(str, "pcie_bus_peer2peer", 18)) {
+				pcie_bus_config = PCIE_BUS_PEER2PEER;
 			} else {
 				printk(KERN_ERR "PCI: Unknown option `%s'\n",
 						str);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index f3f94a5..6ab6bd3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1458,12 +1458,24 @@
  */
 void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 {
-	u8 smpss = mpss;
+	u8 smpss;
 
 	if (!pci_is_pcie(bus->self))
 		return;
 
+	if (pcie_bus_config == PCIE_BUS_TUNE_OFF)
+		return;
+
+	/* FIXME - Peer to peer DMA is possible, though the endpoint would need
+	 * to be aware to the MPS of the destination.  To work around this,
+	 * simply force the MPS of the entire system to the smallest possible.
+	 */
+	if (pcie_bus_config == PCIE_BUS_PEER2PEER)
+		smpss = 0;
+
 	if (pcie_bus_config == PCIE_BUS_SAFE) {
+		smpss = mpss;
+
 		pcie_find_smpss(bus->self, &smpss);
 		pci_walk_bus(bus, pcie_find_smpss, &smpss);
 	}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8c230cb..9fc0122 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -621,8 +621,9 @@
 extern void pcie_bus_configure_settings(struct pci_bus *bus, u8 smpss);
 
 enum pcie_bus_config_types {
-	PCIE_BUS_PERFORMANCE,
+	PCIE_BUS_TUNE_OFF,
 	PCIE_BUS_SAFE,
+	PCIE_BUS_PERFORMANCE,
 	PCIE_BUS_PEER2PEER,
 };