diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 02eb0ef..0885d4a 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -241,6 +241,12 @@
  * 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