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

[Adrian Bunk <bunk@kernel.org>]

On Wed, Jan 09, 2008 at 10:17:24AM -0800, Zachary Amsden wrote:
> On Wed, 2008-01-09 at 16:27 +0100, Rene Herman wrote:
> > On 09-01-08 06:30, Christer Weinigel wrote:
> > I'd not expect very time crtical. The current outb_p use gives a delay 
> > somewhere between .5 and 2 microseconds as per earlier survey meaning a 
> > udelay(1) or 2 would be enough -- again, at the point that udelay() is sensible.
> > 
> > New machines don't use the legacy PIC anymore anyway.
> > 
> > > The floppy controller code uses outb_p.  Even though there might be
> > > floppy controllers on modern systems, I'd rather leave the floppy code
> > > alone since it's supposed to be very fragile.  If you still use
> > > floppies you deserve what you get.
> > 
> > Floppies forever. In practice, leaving it alone isn't going to matter, but 
> > in that same practice changing it to udelay() probably doesn't either. The 
> > ones to leave alone are the ones that are clumsy/impossible to test and the 
> > ones such as in NIC drivers that were specifically tuned.
> 
> I'm speaking specifically in terms of 64-bit platforms here.  Shouldn't
> we unconditionally drop outb_p doing extra port I/O on 64-bit
> architectures?  Especially considering they don't even have an ISA bus
> where the decode timing could even matter?
>...

I don't think the latter statement was true - AFAIR there are Alphas 
with ISA slots.

> Agree.
> 
> Zach

cu
Adrian

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