diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5485883..59036a8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -78,7 +78,7 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
 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_TUNE_OFF;
+enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_AUTO;

 /*
  * The default CLS is used if arch didn't set CLS explicitly and not
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e8b7d5e..6cbfbe1 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1467,6 +1467,19 @@ static int pcie_find_smpss(struct pci_dev *dev, void *data)
 	return 0;
 }

+static int pcie_find_min_mpss(struct pci_dev *dev, void *data)
+{
+	u8 *mpss = data;
+
+	if (!pci_is_pcie(dev))
+		return 0;
+
+	if (*mpss > dev->pcie_mpss)
+		*mpss = dev->pcie_mpss;
+
+	return 0;
+}
+
 static void pcie_write_mps(struct pci_dev *dev, int mps)
 {
 	int rc;
@@ -1560,6 +1573,7 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
 void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 {
 	u8 smpss;
+	u8 mps = pcie_get_mps(bus->self) >> 8;

 	if (!pci_is_pcie(bus->self))
 		return;
@@ -1581,7 +1595,19 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 	case PCIE_BUS_PEER2PEER:
 		smpss = 0;
 		break;
-
+	case PCIE_BUS_AUTO:
+		smpss = bus->self->pcie_mpss;
+		pci_walk_bus(bus, pcie_find_min_mpss, &smpss);
+		if (mps > smpss) {
+			dev_info(&bus->dev,
+				"Current mps %d used in bus 0x%02x is larger than children devices mpss %d support\n"
+				"Please use the pci=pcie_bus_safe boot parameter for safe\n",
+				128 << mpss, bus->number, 128 << smpss);
+			return;
+		}
+		else
+			pci_walk_bus(bus, pcie_bus_configure_set, &mps);
+		return;
 	case PCIE_BUS_SAFE:
 		smpss = mpss;

@@ -1594,8 +1620,6 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 		return;
 	}

-	}
-
 	pcie_bus_configure_set(bus->self, &smpss);
 	pci_walk_bus(bus, pcie_bus_configure_set, &smpss);
 }
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 7a451ff..539b7e4 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2787,7 +2787,8 @@ static void __devinit quirk_intel_mc_errata(struct pci_dev *dev)
 	int err;
 	u16 rcc;

-	if (pcie_bus_config == PCIE_BUS_TUNE_OFF)
+	if (pcie_bus_config == PCIE_BUS_TUNE_OFF ||
+		pcie_bus_config == PCIE_AUTO_AUTO)
 		return;

 	/* Intel errata specifies bits to change but does not say what they are.
diff --git a/include/linux/pci.h b/include/linux/pci.h
index be1de01..84c4ab1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -661,6 +661,7 @@ extern void pcie_bus_configure_settings(struct pci_bus *bus, u8 smpss);

 enum pcie_bus_config_types {
 	PCIE_BUS_TUNE_OFF,
+	PCIE_BUS_AUTO,
 	PCIE_BUS_SAFE,
 	PCIE_BUS_PERFORMANCE,
 	PCIE_BUS_PEER2PEER,