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Message-ID: <4B57A2D4.9030204@gmail.com>
Date: Wed, 20 Jan 2010 18:41:56 -0600
From: Robert Hancock <hancockrwd@gmail.com>
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To: Bastien Nocera <hadess@hadess.net>
CC: linux-kernel <linux-kernel@vger.kernel.org>, pjones@redhat.com
Subject: Re: [PATCH] Disable i8042 checks on Intel Apple Macs
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On 01/20/2010 12:23 PM, Bastien Nocera wrote:
> As those computers never had any i8042 controllers, and the
> current lookup code could potentially lock up/hang/wait for
> timeout for long periods of time.
>
> Fixes intermittent hangs on boot on a MacbookAir1,1
>
> Signed-off-by: Bastien Nocera<hadess@hadess.net>

I assume this is happening because of this code in 
drivers/input/serio/i8042-x86ia64io.h:

         if (!i8042_pnp_kbd_devices && !i8042_pnp_aux_devices) {
                 i8042_pnp_exit();
#if defined(__ia64__)
                 return -ENODEV;
#else
                 printk(KERN_INFO "PNP: No PS/2 controller found. 
Probing ports directly.\n");
                 return 0;
#endif

In other words, on x86, if PNP and/or ACPI don't indicate any PS/2 
controller exists, we randomly bang on the ports in the expectation 
they'll be there anyway. This seems rather misguided. It would seem like 
a better idea to fix this rather than adding yet another DMI list 
(especially since there likely are, or will be, machines without i8042 
other than Macs).

I can see continuing on and probing if PNP isn't present on the machine, 
but certainly if ACPI is enabled, I don't think we should be doing such 
things.
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