Public bug reported:
I have a Google (Asus) Nexus 7. If I use "System Settings...." ->
"Brightness & Lock" to change the screen brightness the brightness
changes as I move the cursor but goes back to minimum brightness as soon
as I stop moving the cursor.
If I try to set the brightness by hand I see the same thing.
stuart@stuart-nexus7:~$ cat /sys/class/backlight/*/brightness
0
stuart@stuart-nexus7:~$ echo 128 | sudo tee /sys/class/backlight/*/brightness
128
stuart@stuart-nexus7:~$ cat /sys/class/backlight/*/brightness
0
It is /usr/bin/luxd that is broken. It reads
/sys/bus/i2c/drivers/al3010/2-001c/show_lux, divides the result by 100
and sets /sys/class/backlight/pwm-backlight/brightness to the resulting
value. Under normal office lighting:
stuart@stuart-nexus7:/etc$ cat /sys/bus/i2c/drivers/al3010/2-001c/show_lux
38
Under a bright lamp:
stuart@stuart-nexus7:/etc$ cat /sys/bus/i2c/drivers/al3010/2-001c/show_lux
127
stuart@stuart-nexus7:/etc$ echo $(($(cat
/sys/bus/i2c/drivers/al3010/2-001c/show_lux) / 100))
1
Dividing show_lux by 100 to get brightness seems incorrect as show_lux
seems to go up to about 127 and brightness goes from 0 to 255.
I fixed the problem by killing luxd. In any case I don't a need a shell
script looping once a second as my Nexux 7 is already too slow.
ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: ubuntu-defaults-nexus7 0.52
Uname: Linux 3.1.10-9-nexus7 armv7l
ApportVersion: 2.8-0ubuntu4
Architecture: armhf
Date: Tue Feb 5 14:38:45 2013
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-defaults-nexus7
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.init.luxd.conf: 2013-02-05T14:26:59.308357
upstart.alsa-restore.override: manual
upstart.alsa-store.override: manual
** Affects: ubuntu-defaults-nexus7 (Ubuntu)
Importance: Undecided
Status: New
** Tags: apport-bug armhf raring running-unity
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https://bugs.launchpad.net/bugs/1116272
Title:
luxd always sets the screen to minimum brightness
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