1 files changed, 21 insertions, 1 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 59011ce9840f..6258f6f24983 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1788,13 +1788,33 @@ void pci_bus_release_busn_res(struct pci_bus *b)
 struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
                 struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {
+        struct pci_host_bridge_window *window;
+        bool found = false;
         struct pci_bus *b;
+        int max;
+
+        list_for_each_entry(window, resources, list)
+                if (window->res->flags & IORESOURCE_BUS) {
+                        found = true;
+                        break;
+                }
 
         b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
         if (!b)
                 return NULL;
 
-        b->busn_res.end = pci_scan_child_bus(b);
+        if (!found) {
+                dev_info(&b->dev,
+                 "No busn resource found for root bus, will use [bus %02x-ff]\n",
+                        bus);
+                pci_bus_insert_busn_res(b, bus, 255);
+        }
+
+        max = pci_scan_child_bus(b);
+
+        if (!found)
+                pci_bus_update_busn_res_end(b, max);
+
         pci_bus_add_devices(b);
         return b;
 }