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Laptop: Toshiba R630
OS: Linux Mint 14 Cinnamon

I have seen various articles (http://askubuntu.com/questions/151651/brightness-is-reset-to-maximum-on-every-restart) on adjusting brightness. But my laptop seems to have more than one way to adjust brightness using /sys fs.

/sys/class/backlight$ ls -l
total 0
lrwxrwxrwx 1 root root 0 Feb 24 11:56 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
lrwxrwxrwx 1 root root 0 Feb 24 12:18 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
lrwxrwxrwx 1 root root 0 Feb 24 12:18 toshiba -> ../../devices/LNXSYSTM:00/device:00/TOS6208:00/backlight/toshiba
  1. why is there more than one way? what is the difference between them?
  2. which is the preferred way to set initial brightness for all run levels?
  3. how does toshset get installed? i dont remember installing myself. Does Mint install based on identified manufacturer?
$ dpkg -l | g toshset
ii  toshset                                     1.76-4                                    amd64        Access much of the Toshiba laptop hardware interface

$ dpkg -L toshset
/.
/etc
/etc/pm
/etc/pm/sleep.d
/etc/pm/sleep.d/novatel_3g_suspend
/usr
/usr/share
/usr/share/doc
/usr/share/doc/toshset
/usr/share/doc/toshset/supported-models.txt
/usr/share/doc/toshset/README.IrDA
/usr/share/doc/toshset/copyright
/usr/share/doc/toshset/README.video
/usr/share/doc/toshset/toshiba-acpi
/usr/share/doc/toshset/toshiba-acpi/2.6.28
/usr/share/doc/toshset/toshiba-acpi/2.6.28/Makefile
/usr/share/doc/toshset/toshiba-acpi/2.6.28/toshiba_acpi.c
/usr/share/doc/toshset/toshiba-acpi/2.6.28/install.sh
/usr/share/doc/toshset/toshiba-acpi/2.6.26
/usr/share/doc/toshset/toshiba-acpi/2.6.26/Makefile
/usr/share/doc/toshset/toshiba-acpi/2.6.26/toshiba_acpi.c
/usr/share/doc/toshset/toshiba-acpi/2.6.26/install.sh
/usr/share/doc/toshset/README
/usr/share/doc/toshset/changelog.Debian.gz
/usr/share/doc/toshset/README.Debian
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/toshset.1.gz
/usr/share/man/man1/toshsat1800-irdasetup.1.gz
/usr/sbin
/usr/sbin/toshsat1800-irdasetup
/usr/bin
/usr/bin/toshset
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1 Answer 1

What you should do is modify the brightness manually, while checking which brightness file is modified.

e.g.

$ ls -l
total 0
lrwxrwxrwx 1 root root 0 Feb 24 14:02 dell_backlight -> ../../devices/platform/dell-laptop/backlight/dell_backlight
lrwxrwxrwx 1 root root 0 Feb 24 14:02 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight

Change the brightness and check to see which file is being modified:

$ cat intel_backlight/brightness 
978

Then whichever is being modified, preset it in rc.local:

$ cat /etc/rc.local
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
echo 978 > /sys/class/backlight/intel_backlight/brightness
exit 0

That worked for me on my Dell and was different to the answer provided in that question you linked to.

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thank you for your answer. the intel_backlight works for me. I was to figure that out earlier. But what i wanted to find out was why do I have three ways to configure brightness and some work and some do not. –  rag Feb 28 '13 at 22:45
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