linux-kernel - Re: [PATCH v4] 8042: Enable A20 using KBC to fix S3 resume on some MSI laptops

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Date:	Tue, 11 Dec 2012 16:45:31 -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,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH v4] 8042: Enable A20 using KBC to fix S3 resume on some
 MSI laptops

Looks good to me.  Alan/Rafael/Dmitry, OK for me to commit this?

	-hpa

On 12/11/2012 01:18 PM, Ondrej Zary wrote:
> Some MSI laptop BIOSes are broken - INT 15h code uses port 92h to enable A20
> line but resume code assumes that KBC was used.
> The laptop will not resume from S3 otherwise but powers off after a while
> and then powers on again stuck with a blank screen.
> 
> Fix it by enabling A20 using KBC in i8042_platform_init for x86.
> 
> Fixes https://bugzilla.kernel.org/show_bug.cgi?id=12878
> 
> Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
> ---
>  drivers/input/serio/i8042-x86ia64io.h |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/input/serio/i8042-x86ia64io.h b/drivers/input/serio/i8042-x86ia64io.h
> index d6cc77a..5f306f7 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 +961,14 @@ 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);
> +	i8042_command(NULL, 0x00ff);	/* Null command for SMM firmware */
>  #endif /* CONFIG_X86 */
>  
>  	return retval;
> 

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