[Intrepid] SRU: Backport fix for handling the brightness control on acer-wmi

[Amit Kucheria]

On Mon, May 11, 2009 at 06:49:02PM +0200, Stefan Bader wrote:
> SRU justification:
>
> Impact: With the introduction of the upstream acpi backlight handling we  
> introduced a inverse check which causes the acer-wmi driver only to be 
> active if the acpi driver is present.
>
> Fix: Invert the check.
>
> Testcase: Without acpi support on acer laptops, there is no backlight 
> control device.
>
> Note: there still seems to be another problem with the acer-wmi interface 
> in general but this is definitely a required step to the solution.
>
> -- 
>
> When all other means of communication fail, try words!
>
>

> From a85bc3c07f08ce066b129d0b9c83f4cb252a3a83 Mon Sep 17 00:00:00 2001
> From: Michael Spang <mspang at csclub.uwaterloo.ca>
> Date: Thu, 12 Mar 2009 14:31:34 -0700
> Subject: [PATCH] acer-wmi: fix regression in backlight detection
> 
> Bug: #333386
> 
> commit 1ba869ec581fd9078b684c56c399ffe3d2345e27 upstream
> 
> Currently we disable the Acer WMI backlight device if there is no ACPI
> backlight device.  As a result, we end up with no backlight device at all.
>  We should instead disable it if there is an ACPI device, as the other
> laptop drivers do.  This regression was introduced in febf2d9 ("Acer-WMI:
> fingers off backlight if video.ko is serving this functionality").
> 
> Each laptop driver with backlight support got a similar change around
> febf2d9.  The changes to the other drivers look correct; see e.g.
> a598c82f for a similar but correct change.  The regression is also in
> 2.6.28.
> 
> Signed-off-by: Michael Spang <mspang at csclub.uwaterloo.ca>
> Acked-by: Thomas Renninger <trenn at suse.de>
> Cc: Zhang Rui <rui.zhang at intel.com>
> Cc: Andi Kleen <ak at linux.intel.com>
> Cc: Carlos Corbacho <carlos at strangeworlds.co.uk>
> Cc: Len Brown <len.brown at intel.com>
> Cc: "Rafael J. Wysocki" <rjw at sisk.pl>
> Cc: <stable at kernel.org>		[2.6.28.x]
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  drivers/misc/acer-wmi.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/misc/acer-wmi.c b/drivers/misc/acer-wmi.c
> index e63c2fd..e1bb82f 100644
> --- a/drivers/misc/acer-wmi.c
> +++ b/drivers/misc/acer-wmi.c
> @@ -1242,7 +1242,7 @@ static int __init acer_wmi_init(void)
>  
>  	set_quirks();
>  
> -	if (!acpi_vendor_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
> +	if (acpi_vendor_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
>  			interface->capability &= ~ACER_CAP_BRIGHTNESS;
>  			printk(ACER_INFO "Brightness must be controlled by "
>  					 "generic video driver\n");
> -- 
> 1.5.4.3
> 

> -- 
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> kernel-team at lists.ubuntu.com
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ACK

-- 
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Amit Kucheria, Kernel Engineer || amit at canonical.com
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