1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 3376055f36e7..0885d4abdc62 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -241,6 +241,12 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
  * If the USB subsystem can't allocate sufficient bandwidth to perform
  * the periodic request, submitting such a periodic request should fail.
  *
+ * For devices under xHCI, the bandwidth is reserved at configuration time, or
+ * when the alt setting is selected.  If there is not enough bus bandwidth, the
+ * configuration/alt setting request will fail.  Therefore, submissions to
+ * periodic endpoints on devices under xHCI should never fail due to bandwidth
+ * constraints.
+ *
  * Device drivers must explicitly request that repetition, by ensuring that
  * some URB is always on the endpoint's queue (except possibly for short
  * periods during completion callacks).  When there is no longer an urb
@@ -351,6 +357,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
         if (xfertype == USB_ENDPOINT_XFER_ISOC) {
                 int     n, len;
 
+                /* FIXME SuperSpeed isoc endpoints have up to 16 bursts */
                 /* "high bandwidth" mode, 1-3 packets/uframe? */
                 if (dev->speed == USB_SPEED_HIGH) {
                         int     mult = 1 + ((max >> 11) & 0x03);
@@ -426,6 +433,11 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
                         return -EINVAL;
                 /* too big? */
                 switch (dev->speed) {
+                case USB_SPEED_SUPER:   /* units are 125us */
+                        /* Handle up to 2^(16-1) microframes */
+                        if (urb->interval > (1 << 15))
+                                return -EINVAL;
+                        max = 1 << 15;
                 case USB_SPEED_HIGH:    /* units are microframes */
                         /* NOTE usb handles 2^15 */
                         if (urb->interval > (1024 * 8))