[PATCH 1/1][Oneiric SRU] Platform: Detect samsung laptop quirk when initial level is zero

[Herton Ronaldo Krzesinski]

On Fri, Dec 02, 2011 at 03:17:24PM -0600, Seth Forshee wrote:
> From: John Serock <john.serock at gmail.com>
> 
> This patch depends on the "Platform: Brightness quirk for samsung
> laptop driver" patch from Jason Stubbs. This patch adds a check for an
> initial brightness level of 0; if the level is 0, this patch changes
> the brightness level to 1 before the driver attempts to detect the
> brightness quirk.
> 
> The Samsung N150 netbook experiences the brightness quirk. Without
> Jason's patch, the only brightness levels available on the N150 are 0,
> 1, and 8. This patch ensures that, when the initial brightness level
> is 0, the samsang-laptop driver detects the brightness quirk on the
> N150, thereby making brightness levels 0 through 8 available.
> 
> Signed-off-by: John Serock <john.serock at gmail.com>
> Acked-by: Jason Stubbs <jasonbstubbs at gmail.com>
> Signed-off-by: Matthew Garrett <mjg at redhat.com>
> 
> (cherry picked from commit ba05b237372bad82533d1f717569d1d817ff3c27)
> BugLink: http://bugs.launchpad.net/bugs/810093
> Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
> ---
>  drivers/platform/x86/samsung-laptop.c |   10 ++++++++--
>  1 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
> index c32dc39..e553486 100644
> --- a/drivers/platform/x86/samsung-laptop.c
> +++ b/drivers/platform/x86/samsung-laptop.c
> @@ -404,8 +404,9 @@ static int get_brightness(struct backlight_device *bd)
>  
>  static void check_for_stepping_quirk(void)
>  {
> -	u8 initial_level = read_brightness();
> +	u8 initial_level;
>  	u8 check_level;
> +	u8 orig_level = read_brightness();
>  
>  	/*
>  	 * Some laptops exhibit the strange behaviour of stepping toward
> @@ -414,6 +415,11 @@ static void check_for_stepping_quirk(void)
>  	 * around in set_brightness.
>  	 */
>  
> +	if (orig_level == 0)
> +		set_brightness(1);
> +
> +	initial_level = read_brightness();
> +

He could have avoid calling read_brightness() twice in the case of
orig_level !=0, minor/harmless thing anyway...

Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>

>  	if (initial_level <= 2)
>  		check_level = initial_level + 2;
>  	else
> @@ -427,7 +433,7 @@ static void check_for_stepping_quirk(void)
>  		pr_info("enabled workaround for brightness stepping quirk\n");
>  	}
>  
> -	set_brightness(initial_level);
> +	set_brightness(orig_level);
>  }
>  
>  static int update_status(struct backlight_device *bd)
> -- 
> 1.7.5.4
> 
> 
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-- 
[]'s
Herton