Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

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On 30-12-07 18:06, Ingo Molnar wrote:

* Rene Herman <[email protected]> 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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