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    SubjectRe: [linux-kernel] Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.
    On another topic.  I have indeed determined what device uses port 80 on 
    Quanta AMD64 laptops from HP.

    I had lunch with Jim Gettys of OLPC a week ago; he's an old friend since
    he worked on the original X windows system. After telling him my story
    about port 80, he mentioned that the OLPC XO machine had some issues
    with port 80 which was by design handled by the ENE KBC device on its
    motherboard. He said the ENE was a very desirable chipset for AMD
    designs recommended by Quanta. Richard Smith of OLPC explained to me
    how the KB3700 they use works, and that they use the KB3700 to send POST
    codes out over a serial link during boot up.

    This gave me a reason to take apart my laptop, to discover that it has
    an ENE KB3920 B0 as its EC and KBC. The port interface for the KB3920
    includes listening to port 80 which is then made available to firmware
    on the EC. It is recognized and decoded on the LPC bus, only for
    writes, and optionally can generate an interrupt in the 8051.

    Dumping both the ENE chip, and looking at the DSDT.dsl for my machine, I
    discovered that port 80 is used as an additional parameter for various
    DSDT methods that communicate to the EC, when it is operating in ACPI mode.

    More work is in progress as I play around with this. But the key thing
    is that ACPI and perhaps SMM both use port 80 as part of the base
    function of the chipset.

    And actually, if I had looked at the /sys/bus/pnp definitions, rather
    than /proc/ioports, I would have noticed that port 80 was part of a
    PNP0C02 resource set. That means exactly one thing: ACPI says that
    port 80 is NOT free to be used, for delays or anything else.

    This should make no difference here: it's just one more reason to stop
    using port 80 for delays on modern machines.



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