linux-kernel - Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

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Date:	Tue, 11 Dec 2007 20:16:49 +0100
From:	Pavel Machek <pavel@....cz>
To:	Rene Herman <rene.herman@...access.nl>
Cc:	Andi Kleen <andi@...stfloor.org>,
	"linux-os (Dick Johnson)" <linux-os@...logic.com>,
	David Newall <david@...idnewall.com>,
	Paul Rolland <rol@...917.net>,
	"H. Peter Anvin" <hpa@...or.com>, Krzysztof Halasa <khc@...waw.pl>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"David P. Reed" <dpreed@...d.com>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, rol@...be.net
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64
	with MCP51 laptops

Hi!

>> Anyways it looks like the discussion here is going in a
>> a loop. I had hoped David would post his test results with
>> another port so that we know for sure that the bus aborts (and not port 
>> 80) is the problem on his box. But it looks like
>> he doesn't want to do this. Still removing the bus aborts
>> is probably the correct way to go forward.
>
> Yes, I do also still want to know that. David (Reed)?
>
>> Only needs a patch now. If nobody beats me to it i'll
>> add one later to my tree.
>
> Pavel Machek already posted one. His udelay(8) wants to be less -- 1 or "to 
> be safe" perhaps 2.
>
> http://lkml.org/lkml/2007/12/9/131

2 at least; that's how long outb(0x80) takes on one of my
machines. Actually, ISA can go down to 4MHz, so maybe we should be
using 4 usec.... but I guess I'm paranoid here.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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