Date: Tue, 8 Jan 2008 01:58:36 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "David P. Reed" <dpreed@reed.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Rene Herman <rene.herman@keyaccess.nl>,
       Bodo Eggert <7eggert@gmx.de>, Christer Weinigel <christer@weinigel.se>,
       Ingo Molnar <mingo@elte.hu>, Rene Herman <rene.herman@gmail.com>,
       Paul Rolland <rol@as2917.net>, Pavel Machek <pavel@ucw.cz>,
       Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
       Ingo Molnar <mingo@redhat.com>, rol@witbe.net
Subject: Re: [linux-kernel] Re: [PATCH] x86: provide a DMI based port 0x80
 I/O delay override.
Message-ID: <20080108015836.554bb144@lxorguk.ukuu.org.uk>
In-Reply-To: <4782BC56.9050607@reed.com>
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> The PIT usage for calibrating the delay loop can be moderated, if need 
> by, by using the PC BIOS which by definition uses the PIT correctly it 
> its int 15 function 83 call..   Just do it before coming up in a state 
> where the PC BIOS int 15h calls no longer work.  I gave code to do this 
> in a much earlier message.

And as I've said before we don't know if we have a PC BIOS. If we are
running from a kexec or on a Macintoy with EFI or an Xbox we may not.

As per previous discussions for the PIT we can simply guess a safe
initial udelay value and then tune the real one.

Alan
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