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    SubjectRe: wake up from a serial port
    On Wed, 12 Sep 2007, Michael Mauch wrote:

    > Guennadi Liakhovetski wrote:
    >
    > > Enable wakeup from serial ports, make it run-time configurable over sysfs,
    > > e.g.,
    > >
    > > echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup
    >
    > Interesting, but how does that work from a user's/hardware perspective?
    >
    > Do I have to pull DSR/RI to +12V? Can I use one of the other pins to get
    > these +12V (i.e. a switch and a resistor to shorten these pins is
    > enough)?
    >
    > And probably in the BIOS I have to enable "wake on modem ring" (or
    > something similar)?

    It depends on the hardware. In principle, with this patch _if_ your system
    can suspend while keeping the UART powered on and the interrupt from this
    UART can wake up your system, then using this patch and the command above
    you'll be able to also keep the UART configured, i.e., prevent the driver
    from suspending it during suspend and then an interrupt from this UART
    will wake up the system. How you generate this interrupt - doesn't matter.
    Whether it is a received byte, or a modem line toggle, as long as it
    produces an interrupt, the system will wake up.

    Don't know whether "normal" PCs can do that and if yes - how.

    Thanks
    Guennadi
    ---
    Guennadi Liakhovetski
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