USB: Use bInterfaceNumber in bandwidth allocations.

USB devices do not have to sort interfaces in their descriptors based on
the interface number, and they may choose to skip interface numbers.  The
USB bandwidth allocation code for installing a new configuration assumes
the for loop variable will match the interface number.  Make it use the
interface number (bInterfaceNumber) in the descriptor instead.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 80995ef0868c..cf0a098a5432 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1670,11 +1670,16 @@ int usb_hcd_alloc_bandwidth(struct usb_device *udev,
                         }
                 }
                 for (i = 0; i < num_intfs; ++i) {
+                        struct usb_host_interface *first_alt;
+                        int iface_num;
+
+                        first_alt = &new_config->intf_cache[i]->altsetting[0];
+                        iface_num = first_alt->desc.bInterfaceNumber;
                         /* Set up endpoints for alternate interface setting 0 */
-                        alt = usb_find_alt_setting(new_config, i, 0);
+                        alt = usb_find_alt_setting(new_config, iface_num, 0);
                         if (!alt)
                                 /* No alt setting 0? Pick the first setting. */
-                                alt = &new_config->intf_cache[i]->altsetting[0];
+                                alt = first_alt;
 
                         for (j = 0; j < alt->desc.bNumEndpoints; j++) {
                                 ret = hcd->driver->add_endpoint(hcd, udev, &alt->endpoint[j]);