Ubuntu
linux-lts-trusty package

  1. Bug #1354313
  2. Comment #5

Comment 5 for bug 1354313

Revision history for this message
Edward Lin (airken) wrote :

@kaxing,

Win8 doesn't use ACPI to control backlight but leaves control to gfx driver instead.
If system tells BIOS that it has win8 capability, BIOS will disable ACPI backlight interface.
Linux kernel starts to support Win8 capability after 3.7.
That's why ACPI backlight control works on early kernel version.

For win8 backlight issue, please refer to following article.
http://www.linuxjournal.com/content/july-2013-linux-kernel-news