x86/PCI: for host bridge address space collisions, show conflicting resource

With insert_resource_conflict(), we can learn what the actual conflict is,
so print that info for debugging purposes.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

arch/x86/pci/acpi.c

@@ -122,7 +122,7 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 	struct acpi_resource_address64 addr;
 	acpi_status status;
 	unsigned long flags;
-	struct resource *root;
+	struct resource *root, *conflict;
 	u64 start, end;
 
 	status = resource_to_addr(acpi_res, &addr);
@@ -157,9 +157,12 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 		return AE_OK;
 	}
 
-	if (insert_resource(root, res)) {
+	conflict = insert_resource_conflict(root, res);
+	if (conflict) {
 		dev_err(&info->bridge->dev,
-			"can't allocate host bridge window %pR\n", res);
+			"address space collision: host bridge window %pR "
+			"conflicts with %s %pR\n",
+			res, conflict->name, conflict);
 	} else {
 		pci_bus_add_resource(info->bus, res, 0);
 		info->res_num++;