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

["H. Peter Anvin" <hpa@zytor.com>]

Alan Cox wrote:
> > What about HP PCLan 16/TP+ cards? I have one that runs 24/7 in a 486 box 
> > (2.6.20.6 kernel) and one spare. It has some VLSI HP chip and also ST-NIC 
> > DP83902AV - is that a good candidate for testing?
>
> What are you trying to test. The documentation explicitly says you need
> the delays and that the delays are in bus clocks not microseconds. That
> means the existing code is correct and it needs a delay dependant on the
> ISA bus clock frequency (somewhere between 6 and 12MHz). Note that the
> delay depends on the bus clock frequency not time.
>
> We don't do overclocking, we don't support overclocking, please do not
> overclock your ethernet chip.

However, assuming a bus clock of 6 MHz should be safe (167 ns).

4 bus clocks would be 667 ns, or we can round it up to 1 ms to deal with 
bus delay effects.

None of this really helps with *memory-mapped* 8390, though, since 
memory mapped writes can be posted.  Putting any IOIO transaction in the 
middle has the effect of flushing the posting queues; an MMIO read would 
  also work.  The WD80x3 cards were memory-mapped, in particular (and 
were some of the very first cards supported by Linux.)

	-hpa
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