Message-ID: <4B5E0DFA.8080705@zytor.com>
Date: Mon, 25 Jan 2010 13:32:42 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Vojtech Pavlik <vojtech@suse.cz>
CC: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
       Robert Hancock <hancockrwd@gmail.com>,
       Bastien Nocera <hadess@hadess.net>,
       linux-kernel <linux-kernel@vger.kernel.org>, pjones@redhat.com
Subject: Re: [PATCH] Disable i8042 checks on Intel Apple Macs
References: <1264011793.1735.3683.camel@localhost.localdomain> <4B57A2D4.9030204@gmail.com> <20100121185544.GB11996@core.coreip.homeip.net> <51f3faa71001211339t4652700ct34659c37479cd67e@mail.gmail.com> <20100121221701.GA15293@core.coreip.homeip.net> <20100125163433.GB31957@suse.cz>
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On 01/25/2010 08:34 AM, Vojtech Pavlik wrote:
> 
> Thus I believe that the right fix here is to figure out why the accesses
> to the ports 0x60/0x64 take a long time or forever on a Mac. Is it just
> that the kernel is timing out waiting for the i8042? Or is it something
> more sinister?
> 

In the A20 code in the setup code, I look for 0xFF coming back and
terminate the "wait for ready" loop much sooner than for other values.
0xFF is a *possible* status value, but not a very *likely* one
(especially for repeated reads), as it would represent:

parity error + receive timeout + transmit timeout + keyboard lock +
command + selftest OK + input full + output full.

	-hpa
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