1 files changed, 32 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 2aa04f29e1de..7f94f760dd0c 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -99,6 +99,26 @@ void pcibios_free_controller(struct pci_controller *phb)
                 kfree(phb);
 }
 
+/*
+ * The function is used to return the minimal alignment
+ * for memory or I/O windows of the associated P2P bridge.
+ * By default, 4KiB alignment for I/O windows and 1MiB for
+ * memory windows.
+ */
+resource_size_t pcibios_window_alignment(struct pci_bus *bus,
+                                         unsigned long type)
+{
+        if (ppc_md.pcibios_window_alignment)
+                return ppc_md.pcibios_window_alignment(bus, type);
+
+        /*
+         * PCI core will figure out the default
+         * alignment: 4KiB for I/O and 1MiB for
+         * memory window.
+         */
+        return 1;
+}
+
 static resource_size_t pcibios_io_size(const struct pci_controller *hose)
 {
 #ifdef CONFIG_PPC64
@@ -960,13 +980,14 @@ static void __devinit pcibios_fixup_bridge(struct pci_bus *bus)
                 if (i >= 3 && bus->self->transparent)
                         continue;
 
-                /* If we are going to re-assign everything, mark the resource
-                 * as unset and move it down to 0
+                /* If we're going to reassign everything, we can
+                 * shrink the P2P resource to have size as being
+                 * of 0 in order to save space.
                  */
                 if (pci_has_flag(PCI_REASSIGN_ALL_RSRC)) {
                         res->flags |= IORESOURCE_UNSET;
-                        res->end -= res->start;
                         res->start = 0;
+                        res->end = -1;
                         continue;
                 }
 
@@ -1228,7 +1249,14 @@ void pcibios_allocate_bus_resources(struct pci_bus *bus)
                 pr_warning("PCI: Cannot allocate resource region "
                            "%d of PCI bridge %d, will remap\n", i, bus->number);
         clear_resource:
-                res->start = res->end = 0;
+                /* The resource might be figured out when doing
+                 * reassignment based on the resources required
+                 * by the downstream PCI devices. Here we set
+                 * the size of the resource to be 0 in order to
+                 * save more space.
+                 */
+                res->start = 0;
+                res->end = -1;
                 res->flags = 0;
         }