Brightness problem

[qhorin]

Hi all, I've just installed Backtrack 5 R1 on my Samsung R780 laptop. At first I wasn't able to use any of the Fn combinations, but now I can use all of them except for the brightness one. I cannot set it with Brightness Applet, too. I've looked for a solution over the internet and so I installed hotkey and samsung tools. The first doesn't work with the brightness combination, and the second seems not to work at all, and if I try to run it in system/preferences/samsung tools preferences it says starting samsung... but then nothing happens. I've tried to modify the grub file, but i only managed to get the brightness to the maximum level. I'll post you my grub file text in order to help

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.

GRUB_DEFAULT=0
#GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE=1024x768

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_LINUX_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

I hope you can help me to find a solution to this annoying problem. I apologize for any grammatical error I made, cause I'm not English

[scottm99]

Do you mean that your screen is too bright, or not bright enough? Have you checked the other forums for this problem? BackTrack is a specialized linux distro, so there may be a better video driver available that will help.

[qhorin]

Now the screen is not bright enough. I've searched and tried all the possible solutions...

[Snayler]

I've seen some info about linux and samsung's brightness control not getting along. Sadly I can't recall where I saw it, but I remember reading about the easy-slow-down-manager. Documentation is weak, but there are some tutorials/forum entries about it, so it's just a matter of doing some research. Hope it helps.

[VulpiArgenti]

You can sometimes work around these hot key problems by writing directly to the "class" files. E.g.

 echo 10 > /sys/class/backlight/mbp_backlight/brightness

This works on a MacBook Air - you would need to look for the equivalent files on a Samsung. May also need to play with grub (acpi_backlight=vendor) as you have, plus look at xorg.conf e.g. Section "Device"

Option "RegistryDwords" "EnableBrightnessControl=1"

I've had these issues on a couple of different laptops so I know how frustrating it is!