2 files changed, 39 insertions, 10 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index daac0427bfd5..fc235b02ff27 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1606,7 +1606,6 @@ int usb_hcd_check_bandwidth(struct usb_device *udev,
 		struct usb_interface *new_intf)
 {
 	int num_intfs, i, j;
-	struct usb_interface_cache *intf_cache;
 	struct usb_host_interface *alt = NULL;
 	int ret = 0;
 	struct usb_hcd *hcd;
@@ -1654,15 +1653,8 @@ int usb_hcd_check_bandwidth(struct usb_device *udev,
 			}
 		}
 		for (i = 0; i < num_intfs; ++i) {
-
-			/* Dig the endpoints for alt setting 0 out of the
-			 * interface cache for this interface
-			 */
-			intf_cache = new_config->intf_cache[i];
-			for (j = 0; j < intf_cache->num_altsetting; j++) {
-				if (intf_cache->altsetting[j].desc.bAlternateSetting == 0)
-					alt = &intf_cache->altsetting[j];
-			}
+			/* Set up endpoints for alternate interface setting 0 */
+			alt = usb_find_alt_setting(new_config, i, 0);
 			if (!alt) {
 				printk(KERN_DEBUG "Did not find alt setting 0 for intf %d\n", i);
 				continue;
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index d1e9440799de..99e54586a545 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -64,6 +64,43 @@ MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
 
 
 /**
+ * usb_find_alt_setting() - Given a configuration, find the alternate setting
+ * for the given interface.
+ * @config - the configuration to search (not necessarily the current config).
+ * @iface_num - interface number to search in
+ * @alt_num - alternate interface setting number to search for.
+ *
+ * Search the configuration's interface cache for the given alt setting.
+ */
+struct usb_host_interface *usb_find_alt_setting(
+		struct usb_host_config *config,
+		unsigned int iface_num,
+		unsigned int alt_num)
+{
+	struct usb_interface_cache *intf_cache = NULL;
+	int i;
+
+	for (i = 0; i < config->desc.bNumInterfaces; i++) {
+		if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber
+				== iface_num) {
+			intf_cache = config->intf_cache[i];
+			break;
+		}
+	}
+	if (!intf_cache)
+		return NULL;
+	for (i = 0; i < intf_cache->num_altsetting; i++)
+		if (intf_cache->altsetting[i].desc.bAlternateSetting == alt_num)
+			return &intf_cache->altsetting[i];
+
+	printk(KERN_DEBUG "Did not find alt setting %u for intf %u, "
+			"config %u\n", alt_num, iface_num,
+			config->desc.bConfigurationValue);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(usb_find_alt_setting);
+
+/**
  * usb_ifnum_to_if - get the interface object with a given interface number
  * @dev: the device whose current configuration is considered
  * @ifnum: the desired interface