MAX_CTRL_PL_SIZE
req->req.length = MAX_CTRL_PL_SIZE;
usb_ep_set_maxpacket_limit(&ep->ep, MAX_CTRL_PL_SIZE);
ep->bytes_per_buffer = MAX_CTRL_PL_SIZE;
epctrl_val = (MAX_CTRL_PL_SIZE << GR_EPCTRL_MAXPL_POS) | GR_EPCTRL_EV;
ep->ep.maxpacket = MAX_CTRL_PL_SIZE;