Re: Question about ACPI Video

[Edward Shao <laface.tw@gmail.com>]

On Tue, Jan 26, 2010 at 8:58 AM, Zhang Rui <rui.zhang@intel.com> wrote:
> On Mon, 2010-01-25 at 17:45 +0800, luke lin wrote:
>> Hi all,
>>
>> I read the drivers/acpi/video.c:
>>
>> 895         result = acpi_video_device_lcd_set_level(device, max_level);
>> 896         if (result)
>> 897                 goto out_free_levels;
>> 898
>> 899         result = acpi_video_device_lcd_get_level_current(device, &level);
>> 900         if (result)
>> 901                 goto out_free_levels;
>> 902
>> 903         br->flags._BQC_use_index = (level == max_level ? 0 : 1);
>> 904
>> 905         if (!br->flags._BQC_use_index) {
>> 912                 for (i = 2; i < br->count; i++)
>> 913                         if (level_old == br->levels[i])
>> 914                                 level = level_old;
>> 915                 goto set_level;
>> 916         }
>> why after level == max_level, it will still need set_level again?
>> is this a bug, or it is necessary.
>>
> Because setting the backlight to max_level is just to check if _BQC uses
> indexed value. We need to set the backlight back after this is done.
>
> thanks,
> rui

Hi~

I'm wondering why check (level == max_level) can make sure if _BQC
uses indexed value?
Is it possible that both level and max_level is indexed value?

Thank you very much.

-- 
Best Regards,
Edward
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