xrandr --prop sets backlight to 100%

Bug #1069640 reported by Tomasz Kontusz on 2012-10-22
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
xbacklight (Ubuntu)
Undecided
Unassigned

Bug Description

OS Version:
    Description: Ubuntu 12.10
    Release: 12.10
$ uname -a
Linux beast 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Hardware:
Samsung NP300V5-S06PL (but Samsung doesn't know they made it - don't bother asking them about it. It's like somebody took a non-polish i7 300V5 and slapped polish software on it)
CPU: i7-2670QM
GPU:
 - Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
 - NVIDIA Corporation GF119 [GeForce GT 520MX] (by Optimus, this one is actually disabled with bumblebee)

xrandr --prop is setting backlight to 100%. This has some interesting effects:
 - xbacklight -set X always fades from 100% to requested brightness
 - xbacklight -dec X always works relatively to 100%
 - after switching the screen off and on (for example by a lockscreen), the brightness is set to 100%
 - before upgrade (on 12.04), using fn buttons under Unity was putting it into an endless loop of jumping between max/just a step lower brightness (while eating as much CPU cycles as a single core could give it :-))

sysfs acts funny too:
# cat /sys/class/backlight/acpi_video0/max_brightness
7
# echo 2 > /sys/class/backlight/acpi_video0/brightness # this actually sets the brightness
# cat /sys/class/backlight/acpi_video0/actual_brightness # shouldn't this be 2?
7
# cat /sys/class/backlight/acpi_video0/brightness
2

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1069640/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

tags: added: bot-comment
affects: ubuntu → xbacklight (Ubuntu)
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