/SPEED=(input-rate,output-rate)

    Allows you to control the input and output speed of the line for
    asynchronous ports. To use this qualifier, you must have PHY_IO
    privilege, or the line must already have TT2$M_SETSPEED set.

    Specify one of the following speeds: 50, 75, 100, 134, 150, 300,
    600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 19200, 38400,
    57600, 76800, or 115200. If your line allows split speed, you
    can specify different speeds for input and output. If you only
    specify one speed, it is used for both input and output.