Why does Ubuntu reset brightness settings at the loading screen?

Posted by leugim on Ask Ubuntu See other posts from Ask Ubuntu or by leugim
Published on 2012-06-18T03:50:27Z Indexed on 2012/09/29 9:49 UTC
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Since I first installed Ubuntu 11.10, I noticed that volume and screen brightness get reset every time Ubuntu starts.

Why is this so? And what ways are there to keep brightness and volume levels after rebooting?

I have found some scripts that change the screen-brightness at login. But this is not a good solution since

  • login is slower because it seems to wait until the screen brightness is at the level specified by the script. After entering the password I see the screen brightness go down gradually. Only after this is complete (~1 or 2 seconds) does the background disappear and Unity come up.
  • The screenbrightness is not remembered but instead redefined at login. So it gets remembered for the first part of the boot, then set to MAX and then again re-set to normal value by the script. My boot process is as follows:
    desired brightness: 2 (13,33%) / Max brightness: 15 (100%)
    1. Bios / brightness: OK
    2. GRUB (violet background color, white text) / brightness: OK
    3. Ubuntu loading screen with the dots / brightness: MAX (win7 loads with OK-brightness)
    4. User Login / brightness: MAX
    5. Unity starts / brightness: OK
  • It seems to be more like a temporary patch than a actual solution.

I'm looking for solutions that set the desired brightness permanently and consistently throughout the whole boot-process

After updating to 12.04 the behavior is the same.

I tried

  • setpci -s 02:00.0 F4.B=XX
    The value of F4.B is always '0' regardless of what value I try to set it to (tried 0, ff, f, 5, etc)
  • The solution in this answer does not have any noticeable effect: Desktop doesn't remember brightness settings after a reboot
    The variables at /sys/class/backlight/acpi_video0/ get changed if I use Fn+UP and Fn+DOWN

Any help is appreciated. Thanks!

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