linux-kernel - Re: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3 resume

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Date:	Tue, 11 Dec 2012 12:36:46 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ondrej Zary <linux@...nbow-software.org>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3
 resume

On 12/11/2012 12:29 PM, Ondrej Zary wrote:
> 
> Something like this? (It works.)
> 

Something like that.  We need to make sure we send the proper sequence,
though, or it might break some SMM firmware...

> diff --git a/drivers/input/serio/i8042-x86ia64io.h b/drivers/input/serio/i8042-x86ia64io.h
> index d6cc77a..0807ac7 100644
> --- a/drivers/input/serio/i8042-x86ia64io.h
> +++ b/drivers/input/serio/i8042-x86ia64io.h
> @@ -921,6 +921,7 @@ static int __init i8042_platform_init(void)
>  	int retval;
>  
>  #ifdef CONFIG_X86
> +	u8 a20_on = 0xdf;
>  	/* Just return if pre-detection shows no i8042 controller exist */
>  	if (!x86_platform.i8042_detect())
>  		return -ENODEV;
> @@ -960,6 +961,13 @@ static int __init i8042_platform_init(void)
>  
>  	if (dmi_check_system(i8042_dmi_dritek_table))
>  		i8042_dritek = true;
> +
> +	/*
> +	 * A20 was already enabled during early kernel init. But some buggy
> +	 * BIOSes (in MSI Laptops) require A20 to be enabled using 8042 to
> +	 * resume from S3. So we do it here and hope that nothing breaks.
> +	 */
> +	i8042_command(&a20_on, 0x10d1);
>  #endif /* CONFIG_X86 */
>  
>  	return retval;
> 

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