xfer_len = 0;
ret = libusb_bulk_transfer(usb->devhdl, EP_COMMAND,
(unsigned char *)command, cmd_len * 2,
&xfer_len, USB_TIMEOUT);
if (ret != 0) {
xfer_len = 0;
ret = libusb_bulk_transfer(usb->devhdl, EP_COMMAND,
(unsigned char *)command, cmd_len * 2,
&xfer_len, USB_TIMEOUT);
if (ret != 0) {