1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b1187ff31d8..6ab6bd3df4b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1351,7 +1351,8 @@ static int pcie_find_smpss(struct pci_dev *dev, void *data)
          * will occur as normal.
          */
         if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) ||
-            dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))
+             (dev->bus->self &&
+              dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT)))
                 *smpss = 0;
 
         if (*smpss > dev->pcie_mpss)
@@ -1457,12 +1458,24 @@ 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 = 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);
         }