lkml.org 
[lkml]   [2006]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectBug in 8250/serial_core suspend code.
    Date
    Hi,
    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):
    http://sosdg.org/~coywolf/lxr/source/drivers/serial/serial_core.c?v=2.6;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
    Uli
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-04-26 17:17    [W:0.023 / U:0.228 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site