Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64with MCP51 laptops

[Rene Herman]

On 07-12-07 19:42, Alan Cox wrote:

> On Fri, 07 Dec 2007 19:45:25 +0100
> Rene Herman <rene.herman@xxxxxxxxxxxx> wrote:
>
> > On 07-12-07 18:19, Alan Cox wrote:
> >
> > > On Fri, 7 Dec 2007 17:31:16 +0100
> > > Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
> > >
> > > > > You don't need to. Port 0x80 historically is about 8uS so just udelay(8)
> > > > > and make sure the initial default delay is conservative enough before the
> > > > How would you make it conservative enough handling let's say a 6Ghz CPU
> > > > that can execute multiple jumps per cycle?
> > > Pick a sane worst case and go with it at boot. We don't have to be
> > > accurate before we tune udelay - over long in uSecs isnt going to hurt,
> > > and most post boot _p's can be replaced by udelay(8) now
> > Isn't 8 generally a bit overly long? I believe the norm is 1?
>
> 8uS is an ISA bus transaction.

You very likely know better but just in case you're confused -- I thought it 
was 8 cycles...

Rene.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/