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    SubjectRe: [PATCH] x86: provide a DMI based port 0x80 I/O delay override
    On 30-12-07 18:06, Ingo Molnar wrote:

    > * Rene Herman <rene.herman@keyaccess.nl> wrote:

    >> Real ISA systems will also generally respond faster to it than the
    >> unused port (this thing actually has an ISA bus but not VGA on it
    >> ofcourse) which means that "a perfect delay register" it is not. But
    >> yes, I have an actual Am386DX-40 with ISA VGA up and running which
    >> also doesn't care either way, about the ones in misc_32.c or anywhere
    >> else for that matter.
    >
    > yeah - and that's typical of most _p() use: most of them are totally
    > bogus, but the global existence of the delay was used as a "it _might_
    > break system" boogey-man against replacing it.

    No delaying at all does break a few systems.

    > so _IF_ we do any delay in x86 platform drivers, we at most do a delay
    > on the order of the round-trip latency to the same piece of hardware we
    > are handling.

    Given that part of the problem is 2 MHz devices on a 8 MHz bus, you can't do
    this generally.

    Rene.


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