I noticed that running manually xrandr --output LVDS1 --set BACKLIGHT 0 makes the screen brightness maximum.
If I boot without acpi=off and run the xrandr-command, nothing happends. None of the Fn-key work either as acpi is on, so I guess the ACPI is broken. To make the screen as dim as possible, run xrandr --output LVDS1 --set BACKLIGHT 2948310 Maybe the range should be the other way around, 0 as minimum lightness? $ xrandr --prop Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192 LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm EDID: 00ffffffffffff000daf991500000000 07140103802213780a3d9594564f8e28 26505400000001010101010101010101 0101010101017a1d56d250001e303c28 360058c110000018000000fe004e3135 3642332d4c30420a2020000000fe0043 4d4f0a202020202020202020000000fe 004e31353642332d4c30420a20200048 BACKLIGHT: 1 (0x00000001) range: (0,2948310) Backlight: 1 (0x00000001) range: (0,2948310) scaling mode: Full aspect supported: None Full Center Full aspect 1366x768 60.0*+ 1360x768 59.8 60.0 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 As a workaround I tried to add xrandr --output LVDS1 --set BACKLIGHT 0 -display :0 to /etc/rc.local but it does not work (error says cookie mismatch). A less optimal workaround I added the command to the Gnome session, but LDM starts out dimmed, so the sole user of the laptop has to enter their password blindly (screen is to dark to see almost anything). -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/910536 Title: Screen too dark, no backlight, unusable X To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/910536/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp