Re: PATCH for Broken PCI Multi-IO in 2.4.3 (serial+parport)

From: Jeff Garzik (jgarzik@mandrakesoft.com)
Date: Sat Apr 07 2001 - 17:52:28 EDT

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    Gunther Mayer wrote:
    >
    > Jeff Garzik wrote:
    > >
    > Like I mentioned in a
    > > previous message, the Via parport code is ugly and should go into a Via
    > > superio driver. It is simply not scalable to consider the alternative
    > > -- add superio code to parport_pc.c for each ISA bridge out there. I
    > > think the same principle applies to this discussion as well.
    >
    > Yes, superio will go away and replaced by user level utility:
    > http://home.t-online.de/home/gunther.mayer/lssuperio-0.61.tar.bz2

    The entire point of superio is -not- configuration. That's what your
    BIOS setup does, and/or user-level utilities.

    The point of superio support is that you can obtain 100% accurate probe
    information for legacy ISA devices, by looking at the information
    exported by the ISA bridge. There is no need for "probing" per se,
    because you know whether or not the parallel port is enabled, exactly
    what IRQ it's on, and exactly what DMA channel it uses.

    So, a superio probe occurs first because it provides the maximum
    information at the least cost. Since ISA devices must still be
    supported, the ISA probe should come after the PCI probe (which includes
    PCI superio stuff). ISA probes to ports already registered via the
    superio probe fail at the request_region level, avoiding any unnecessary
    hardware access at those ports. There are tertiary benefits to such a
    scheme as well, I'll be glad to elaborate on if people are interested in
    the nitty gritty (read: boring) details.

            Jeff

    -- 
    Jeff Garzik       | Sam: "Mind if I drive?"
    Building 1024     | Max: "Not if you don't mind me clawing at the dash
    MandrakeSoft      |       and shrieking like a cheerleader."
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