I usually have laptop-mode tools configure my brightness. Essentially, it sets the brightness to 12 on AC and 7 on battery. This worked fine until a recent update. This coincided with the upgrade to the latest kernel in the stable repo but I'm not sure the kernel is responsible.
Basically, when I boot, brightness is now at 100% (15). If I remove the AC, brightness is correctly set to 7. If I replace the AC, brightness is correctly set to 12. So this is hardly an insurmountable problem. However, it is annoying me that I can't figure out what is overriding my settings all of a sudden since it worked perfectly before.
Other packages upgraded at the same time include:
[2013-01-23 19:18] upgraded cairo (1.12.10-1 -> 1.12.10-2) [2013-01-23 19:18] upgraded libglapi (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded libgl (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded intel-dri (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded khrplatform-devel (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded lib32-cairo (1.12.8-1 -> 1.12.10-1) [2013-01-23 19:18] upgraded lib32-icu (50.1.1-1 -> 50.1.2-1) [2013-01-23 19:18] upgraded lib32-harfbuzz (0.9.9-1 -> 0.9.9-2) [2013-01-23 19:18] upgraded lib32-libxi (1.6.1-1 -> 1.6.2-1) [2013-01-23 19:18] upgraded libgbm (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded libegl (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:18] upgraded libgles (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:20] upgraded linux-lts (3.0.59-1 -> 3.0.60-1) [2013-01-23 19:20] upgraded mesa (9.0.1-1 -> 9.0.2-1) [2013-01-23 19:20] upgraded refind-efi (0.6.4-1 -> 0.6.5-1)
but it might have been something upgraded shortly before this if it wasn't something which would have made me reboot. I'm wondering about intel-dri or the kernel but I'm not sure what the others do and, as I say, it could be something else.
I use KDE but in system settings, KDE is set not to automatically change the brightness for AC/battery/low battery although KDE is meant to dim the screen after a period of inactivity.
$ systemctl status laptop-mode.service laptop-mode.service - Laptop Mode Tools Loaded: loaded (/usr/lib/systemd/system/laptop-mode.service; enabled) Active: active (exited) since Sul 2013-01-27 02:53:20 GMT; 24min ago Process: 1078 ExecStart=/usr/sbin/laptop_mode init auto (code=exited, status=0/SUCCESS)
I am not sure exactly what his changed, as you are a kde user. So I am sure there was something that was handing this for you on boot. But just to throw it out there, since you have no responses as of yet, I use a udev rule to set the brightness lower on boot. Though I just usually keep my brightness pretty low.
I know you keep your brightness at different levels depending on what power source is currently in use. So maybe you could write two udev rules. One would have an action if /sys/class/power_supply/AC/online is a 1 and another if the file contains a 0.
The only problem with this is that you obviously would not be solving the original problem, but rather just working around it.
Thanks. I might try that except that I just rebooted for the glibc upgrade and my brightness is set correctly again. But if it doesn't last, I think I might just consider switching to udev rules for brightness although I think laptop-mode tools has slightly finer grain (3 modes). Then again, I only ever use 2 so it hardly matters.