Re: [PATCH] acpi: fix brightness level is initialized to zero when BIOS does not restore the brightness value to _BQC.

[joeyli <jlee@suse.com>]

Hi Alex, 

於 一，2012-10-01 於 13:39 +0800，Alex Hung 提到：
> Signed-off-by: Alex Hung <alex.hung@canonical.com>
> ---
>  drivers/acpi/video.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index 42b226e..eaa9573 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -724,6 +724,10 @@ acpi_video_init_brightness(struct acpi_video_device *device)
>  				if (level_old == br->levels[i])
>  					level = level_old;
>  		}
> +
> +		if (level == 0)
> +			level = br->levels[(br->count) / 2 + 1];

Looks here used the 50% brightness level.

Per comment in video.c, we want set the backlight to max_level when
level_old is invalid:

        if (!br->flags._BQC_use_index) {
                /*
                 * Set the backlight to the initial state.
                 * On some buggy laptops, _BQC returns an uninitialized value
                 * when invoked for the first time, i.e. level_old is invalid.
                 * set the backlight to max_level in this case
                 */

I think here used max_level to fulfill it, e.g.
	
+		if (level == 0)
+			level = max_level;

How do you think?

> +
>  		goto set_level;
>  	}
>  

Thanks a lot!
Joey Lee




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