linux-kernel - Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A

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Date:	Mon, 29 Jul 2013 22:17:54 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Felipe Contreras <felipe.contreras@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	Len Brown <lenb@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A

On Monday, July 29, 2013 02:20:58 PM Felipe Contreras wrote:
> Since v3.7 the acpi backlight driver doesn't work at all on this machine
> because presumably the ACPI code contains stub code when Windows 8 OSI is
> reported.
> 
> The commit ea45ea7 (in v3.11-rc2) tried to fix this problem by using the intel
> backlight driver, however, on this machine it turns the backlight completely
> off when it reaches level 0%, after which the user might have a lot trouble
> trying to bring it back.
> 
> This patch fixes both regressions by blacklisting the win8 OSI, so we are back
> to v3.6 behavior, and it should remain that way until the intel backlight
> driver is fixed.

Well, it really is a workaround, so perhaps it would be fair to call it this
way?

> Since v3.7, users have been forced to fix the initial regression by modifying
> the boot arguments [1].
> 
> [1] https://wiki.archlinux.org/index.php/ASUS_Zenbook_Prime_UX31A
> 
> Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>

I don't really feel this is the right approach, but then I don't care enough
to fight with you. :-)

I'll queue up this patch for 3.12.

Thanks,
Rafael


> ---
>  drivers/acpi/blacklist.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/acpi/blacklist.c b/drivers/acpi/blacklist.c
> index cb96296..a404127 100644
> --- a/drivers/acpi/blacklist.c
> +++ b/drivers/acpi/blacklist.c
> @@ -192,6 +192,12 @@ static int __init dmi_disable_osi_win7(const struct dmi_system_id *d)
>  	acpi_osi_setup("!Windows 2009");
>  	return 0;
>  }
> +static int __init dmi_disable_osi_win8(const struct dmi_system_id *d)
> +{
> +	printk(KERN_NOTICE PREFIX "DMI detected: %s\n", d->ident);
> +	acpi_osi_setup("!Windows 2012");
> +	return 0;
> +}
>  
>  static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
>  	{
> @@ -267,6 +273,14 @@ static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
>  		     DMI_MATCH(DMI_PRODUCT_NAME, "Satellite P305D"),
>  		},
>  	},
> +	{
> +	.callback = dmi_disable_osi_win8,
> +	.ident = "ASUS Zenbook Prime UX31A",
> +	.matches = {
> +		     DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
> +		     DMI_MATCH(DMI_PRODUCT_NAME, "UX31A"),
> +		},
> +	},
>  
>  	/*
>  	 * BIOS invocation of _OSI(Linux) is almost always a BIOS bug.
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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