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    SubjectBug in 8250/serial_core suspend code.
    there is a bug in recent kernel's suspend code for serial drivers, at least
    for 8250 and pxa, probably others though.

    When suspending (e.g. apm --suspend) a machine, the serial_core suspend code
    tries to disable modem control lines (including RTS):;a=arm#L1926
    This is needed to stop the other side of a serial link from sending any data
    after our serial port has been disabled.

    Now in line 1937 ops->shutdown(port) is called. For 8250 this points to
    serial8250_shutdown, for pxa to serial_pxa_shutdown. Both call
    xxx__set_mctrl(&up->port, up->port.mctrl) which will restore the old control
    line values and reverse the intended effect.

    I am not quite sure about the right approach to fixing this. Should
    uart_suspend_port set port.mctrl to 0 after saveing it's old value? Or should
    serial8250_shutdown simply set port.mctrl to 0?

    Please also reply in private mail, as I am not subscribed.

    Thanks for your help
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      Last update: 2006-04-26 17:17    [W:0.021 / U:54.856 seconds]
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