mraa_uart_set_flowcontrol(): rogue XOFF byte

[ric96]

HI,
I am trying to setup uart on a DragonBoard410c, and I've set flow-control to off. but as soon as I call mraa_uart_set_flowcontrol() it sends a XOFF byte on the tx line.

unsigned int ctsrts = 0, xonxoff = 0;
status = mraa_uart_set_flowcontrol(uart, xonxoff, ctsrts);
    if (status != MRAA_SUCCESS) {
        goto err_exit;
    }