Backlight brightness level reverts to default after lid re-open

[John Karp]

Binary package hint: acpi

I have a Lenovo T61, and I can set the backlight levels just fine with the special keys. However, whenever I close and re-open the lid, the brightness level returns to the default, which is very dim. The brightness level should be preserved instead.

I have the GM965/GL960 Intel graphics controller.

Ubuntu 8.04.1
Linux kaze 2.6.24-19-generic #1 SMP Wed Jun 18 14:15:37 UTC 2008 x86_64 GNU/Linux

[Zorael (zorael)]

I can confirm this on my Advent 4211 (rebranded MSI Wind netbook), though when I reopen the lid it defautls back to 100%. I like to use mine at lower settings - especially on evenings.

KDE 8.04.1.
         $ uname -a
         Linux tleilax 2.6.24-21-generic #1 SMP Mon Aug 25 17:32:09 UTC 2008 i686 GNU/Linux

         $ apt-cache policy kdm
         kdm:
           Installed: 4:3.5.10-0ubuntu1~hardy1
           Candidate: 4:3.5.10-0ubuntu1~hardy1
           Version table:
          *** 4:3.5.10-0ubuntu1~hardy1 0
                 500 http://se.archive.ubuntu.com hardy-backports/main Packages
                 100 /var/lib/dpkg/status
              4:3.5.9-0ubuntu7.3 0
                 500 http://se.archive.ubuntu.com hardy-updates/main Packages
              4:3.5.9-0ubuntu7 0
                 500 http://se.archive.ubuntu.com hardy/main Packages

Moreover, the (KDE) power manager, which seems to manage the keybinds for raising and lowering the brightness, stops working if brightness is set to 0% before closing. The manager still *thinks* it's at 0%, while it's actually at 100%, so the keybinds no longer work. The popup spawns saying "0%", but it won't raise. Changing /proc/acpi/video/*/LCD/brightness to anything other than the minimum value (20 for me) makes it work again. So to not lose control over brightness setting as a non superuser, I have to make sure it's not at the lowest setting when closing the lid. Superuser permissions is required to fix it.

I tried modifying /etc/acpi/lid.sh to copy the /proc brightness file upon lid close and restore it upon opening, but it seems that at some point in the lid-close scripts it *sets* the brightness to 20. No matter what setting I had it always saved my temporary file with "20". I'm not sure why.

         grep current /proc/acpi/video/IGD/LCD/brightness | awk -F": " '{ print $2 }'

Anyway, even with those extra lines in the script resetting the brightness to 20 upon opening, it automatically rises to 100% as soon as I move the mouse or press any key.

[RoundSparrow (stephen-roundsparrow)]

I can confirm this with the latest Ubuntu Beta 8.10 (updated 2008-10-18) on Asus eee 1000H, latest BIOS.

[Zorael (zorael)]

Reconfirming, happens for me in Ubuntu 8.10, Kubuntu 8.10, Mint 8.10 and Xubuntu 8.10. It also occurs when I use (Ctrl+)Alt+Fx to switch to tty. Switching *between* ttys works fine, but switching to and from tty - from and to X - reverts brightness to 100% which seems to be my default. Ergo, as soon as X "blanks" the screen (changes mode?), it's reset.

This happens with the intel, nv and proprietary nvidia drivers, tested on two different laptops (Advent 4211, Acer Aspire 9815).

         $ apt-cache policy acpi
         acpi:
           Installed: 1.1-1ubuntu1
           Candidate: 1.1-1ubuntu1
           Version table:
          *** 1.1-1ubuntu1 0
                 500 http://archive.ubuntu.com intrepid/main Packages
                 100 /var/lib/dpkg/status

         $ uname -a
         Linux tleilax 2.6.27-10-generic #1 SMP Fri Nov 21 12:00:22 UTC 2008 i686 GNU/Linux

[Zorael (zorael)]

Still prevalent in kernel 2.6.27-11(.14). Brightness is reset to 100% when switching between tty and X, and when closing and opening the lid.

       $ apt-cache policy acpi linux-generic
       acpi:
         Installed: 1.1-1ubuntu1
         Candidate: 1.1-1ubuntu1
         Version table:
        *** 1.1-1ubuntu1 0
               500 http://se.archive.ubuntu.com intrepid/main Packages
               100 /var/lib/dpkg/status
       linux-generic:
         Installed: 2.6.27.11.14
         Candidate: 2.6.27.11.14
         Version table:
        *** 2.6.27.11.14 0
               500 http://se.archive.ubuntu.com intrepid-proposed/restricted Packages
               100 /var/lib/dpkg/status
            2.6.27.9.13 0
               500 http://se.archive.ubuntu.com intrepid-updates/restricted Packages
               500 http://security.ubuntu.com intrepid-security/restricted Packages
            2.6.27.7.11 0
               500 http://se.archive.ubuntu.com intrepid/restricted Packages

       $ uname -a
       Linux tleilax 2.6.27-11-generic #1 SMP Fri Dec 19 16:29:52 UTC 2008 i686 GNU/Linux