+#if defined(CONFIG_CMD_USB)
+ /*
+ * turn off USB to prevent the host controller from writing to the
+ * SDRAM while Linux is booting. This could happen (at least for OHCI
+ * controller), because the HCCA (Host Controller Communication Area)
+ * lies within the SDRAM and the host controller writes continously to
+ * this area (as busmaster!). The HccaFrameNumber is for example
+ * updated every 1 ms within the HCCA structure in SDRAM! For more
+ * details see the OpenHCI specification.
+ */
+ usb_stop();
+#endif
+
+