DEFAULT_FS_BURST_CAP_SIZE
buf = DEFAULT_FS_BURST_CAP_SIZE / FS_USB_PKT_SIZE;
dev->rx_urb_size = DEFAULT_FS_BURST_CAP_SIZE;
burst_cap = DEFAULT_FS_BURST_CAP_SIZE / FS_USB_PKT_SIZE;
dev->rx_urb_size = DEFAULT_FS_BURST_CAP_SIZE;