Re: [PATCH] Disable i8042 checks on Intel Apple Macs

From: Robert Hancock
Date: Wed Jan 20 2010 - 19:47:51 EST

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@xxxxxxxxxx>

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

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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