Comment 213 for bug 582809

So, to achieve that behaviour, led_double_tap initially must be 0

pars->led_double_tap = xf86SetBoolOption(opts, "LEDDoubleTap", FALSE);

because when the touchpad is doubled tapped the value of touchpad_off changes:

if (priv->led_tapped) {
        /* double-tapped? */
        diff = TIME_DIFF(priv->led_tap_millis + 400, hw->millis);
        if (diff >= 0) {
            para->touchpad_off = !para->touchpad_off;

I propose the next changes in synaptics.c, in the function static void set_default_parameters(InputInfoPtr pInfo)

pars->led_status = xf86SetBoolOption(opts, "LEDStatus", TRUE);
pars->led_double_tap = xf86SetBoolOption(opts, "LEDDoubleTap", FALSE);