Re: [PATCH 3/3] acpi-video: change acpi-video brightness_switch_enabled default to 0

[Aaron Lu <aaron.lu@intel.com>]

On 05/05/2014 05:38 PM, Hans de Goede wrote:
> acpi-video is unique in that it not only generates brightness up/down
> keypresses, but also (sometimes) actively changes the brightness itself.
> 
> This presents an inconsistent kernel interface to userspace, basically there
> are 2 different scenarios, depending on the laptop model:
> 
> 1) On some laptops a brightness up/down keypress means: show a brightness osd
> with the current brightness, iow it is a brightness has changed notification.
> 
> 2) Where as on (a lot of) other laptops it means a brightness up/down key was
> pressed, deal with it.
> 
> Most of the desktop environments interpret any press as in scenario 2, and
> change the brightness up / down as a response to the key events, causing it
> to be changed twice, once by acpi-video and once by the DE.
> 
> With the new default for video.use_native_backlight we will be moving even
> more laptops over to behaving as in scenario 2. Making the remaining laptops
> even more of a weird exception. Also note that it is hard to detect scenario
> 1 properly in userspace, and AFAIK none of the DE-s deals with it.
> 
> Therefor this commit changes the default of brightness_switch_enabled to 0
> making its behavior consistent with all the other backlight drivers.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Reviewed-by: Aaron Lu <aaron.lu@intel.com>

Note that the Documentation/kernel-parameters.txt has to be modified
accordingly to change the default value for video.brightness_switch_enabled
to 0.

Thanks,
Aaron

> ---
>  drivers/acpi/video.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index cebc74d..34198b2 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -68,7 +68,7 @@ MODULE_AUTHOR("Bruno Ducrot");
>  MODULE_DESCRIPTION("ACPI Video Driver");
>  MODULE_LICENSE("GPL");
>  
> -static bool brightness_switch_enabled = 1;
> +static bool brightness_switch_enabled;
>  module_param(brightness_switch_enabled, bool, 0644);
>  
>  /*
>