--- Comment #11 from Aaron Lu <aaron.lu@...> ---
The ASL code initialize initial brightness level to 100, but only for OS that
is pre-vista. Don't know why it does this...
The _INI method is run during the ACPI device is first discovered.
Method (_INI, 0, NotSerialized) // _INI: Initialize
If (LLess (OSYS, 0x07D6))
Store (0x64, BRTL)
The _BQC method is used to tell the current brightness level
Method (_BQC, 0, NotSerialized) // _BQC: Brightness Query Current
Since it is not initialized in _INI(as we report to firmware we are Windows
2012), the video module thought the initial brightness level is 0 and then set
level 0. The cmdline option use_bios_initial_backlight=0 is used to tell video
module that the initial backlight level firmware reported is wrong and do not
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