Screen Brighitness doesn’t work,what can i do to solve this problem?
Tell us your hardware specifics. Maybe trying to adjust the brightness before booting the os (means in the bios) .
[color=#000080]Usually I solved with these instructions, from a terminal type:[/color]
[size=medium]sudo kate /etc/default/grub[/size]
[color=#000080]Locate and modify or add lines:[/color]
[size=medium]acpi_osi=Linux
acpi_backlight=vendor
GRUB_CMDLINE_LINUX_DEFAULT= “quiet splash acpi_osi=Linux acpi_backlight=vendor”[/size]
[color=#000080]Save and Close Kate.
In the terminal:[/color]
[size=medium]sudo update-grub
sudo reboot[/size]
[color=#000080]Samsung Laptop (which are used) I have this solution:
Install this repository:[/color]
[size=medium]sudo add-apt-repository ppa:voria/ppa
sudo apt-get update
sudo apt-get install samsung-tools[/size]
[color=#000080]To function Fn and the screen brightness keys must then modify the repository changing “Saucy” with “Quantal” and then make a terminal:[/color]
[size=medium]sudo apt-get update
sudo apt-get install samsung-backlight
sudo reboot[/size]
[color=#000080]I hope they can, works for me perfect in Netrunner 13.12 (64bit) and I’ve tried Kubuntu, Mint-KDE without any problem.[/color] 
how can i know my hardware specifics?
I have dell inspiron 5521 core i7
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I have dell inspiron 5521 core i7 , what should i do?
[color=#000080]Usually I solved with these instructions, from a terminal type:[/color]
[size=medium]sudo kate /etc/default/grub[/size]
[color=#000080]Locate and modify or add lines:[/color]
[size=medium]acpi_osi=Linux
acpi_backlight=vendor
GRUB_CMDLINE_LINUX_DEFAULT= “quiet splash acpi_osi=Linux acpi_backlight=vendor”[/size]
[color=#000080]Save and Close Kate.
In the terminal:[/color]
[size=medium]sudo update-grub
sudo reboot[/size]
Hi this is my grub etc:
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=lsb_release -i -s 2> /dev/null || echo Debian
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_DEFAULT=saved
GRUB_CMDLINE_LINUX=“acpi_osi=Linux”
GRUB_CMDLINE_LINUX=“acpi_backlight=vendor”
GRUB_CMDLINE_LINUX_DEFAULT= “quiet splash acpi_osi=Linux acpi_backlight=vendor”
and when I update grub , recieve this error:
/usr/sbin/grub-mkconfig: 7: /etc/default/grub: quiet splash acpi_osi=Linux acpi_backlight=vendor: not found
where is the problem? :huh:
thanks
[color=#000080]I use a Samsung laptop and it works perfect brightness control and combinations with the FN keys.
What machine do you use?
Hi this is my grub etc:[/color]
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=lsb_release -i -s 2> /dev/null || echo Debian
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_DEFAULT=saved
GRUB_CMDLINE_LINUX_DEFAULT=“quiet splash”
GRUB_CMDLINE_LINUX=""
Sony vaio F136FX
Nvidia 425m
my grub etc was’nt like this, I changed it as you said.
But when I try to update grub recive that error and brightness issue still remains.
when I was on ubuntu 12.04 and later I solved the problem with changing Xorg.conf but in this way when the laptop sleeps screen brightness go to 0% and I couldnt see anything unless taping display off//on key on the keyboard and in 3 seconds I must increese brightness or the screen get darks again!! :huh:
so I can fix this problem with Xorg way but it has mentioned problems.
you see this is very bad that gnu/linux has such this essentials problems make me go back to windows 
[color=#000080]It’s just a matter of looking a little “Saint Google”…
The first search I jumped it, explain there to solve your problem.[/color] 
thanks alot
Can you tell me what I should do with these 4 files?
I translated the page with google to english but I can’t understand it
[color=#000080]Run as root (kdesudo dolphin) copy the first two files:[/color]
[size=medium]/etc/acpi[/size]
[color=#000080]Now we enter: [/color][size=medium]/etc/acpi/events,[/size] [color=#000080]and move there the last two.
We must make executable files to work properly:[/color]
[size=medium]sudo chmod +x /etc/acpi/video_brightness*[/size]
[color=#000080]Finally, we need to edit the [/color][size=medium]xorg.conf [/size][color=#000080]file to enable brightness control.
Open the terminal and type the following:[/color]
[size=medium]kdesudo kate /etc/X11/xorg.conf[/size]
[color=#000080]Once in the text editor, look for the Section “Device” section and add the line:[/color]
[size=medium]Option “RegistryDwords” “EnableBrightnessControl=1″[/size]
[color=#000080]As seen in the picture:[/color]
[attachment=121]
[color=#000080]If we have done everything right, when you reboot, you should be able to control both the brightness key combination I mentioned above or from the power manager.[/color]
Thank you, now I can change the brightness
But as I said when the laptop wakes up after closing laptop, the screen gets dark after few seconds and I must press the display on key on the key bord ,then screen turns on and after few seconds turns off again!
Weird! 
[color=#0000CD][size=large][font=Arial]Finally I found the fixation for screen brightness control and after suspend backlight problem for VAIO F series
and I represent it now for every one
1.from a terminal type:
sudo kate /etc/default/grub
Locate and modify or add lines:
acpi_osi=Linux
acpi_backlight=vendor
GRUB_CMDLINE_LINUX_DEFAULT= “quiet splash acpi_osi=Linux acpi_backlight=vendor”
Save and Close Kate.
In the terminal:
sudo update-grub
sudo reboot
but it worked for me ( my grub etc is like this now):
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=lsb_release -i -s 2> /dev/null || echo Debian
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_DEFAULT=saved
GRUB_CMDLINE_LINUX=“acpi_osi=Linux”
GRUB_CMDLINE_LINUX=“acpi_backlight=vendor”
2.and change xorg:
kdesudo kate /etc/X11/xorg.conf
add or modify section device like this:
Section “Device”
Identifier “Default Device”
Driver “nvidia”
Option “NoLogo” “True”
Option “RegistryDwords” “EnableBrightnessControl=1”
EndSection
3.and for suspend backlight:
Open /etc/pm/sleep.d/00-diplayfix in a text editor and paste the following script:
$ kdesudo kate /etc/pm/sleep.d/00-displayfix
Paste this:
#!/bin/sh
case “$1” in
thaw|resume)
echo 500 > /sys/class/backlight/intel_backlight/brightness
;;
*)
;;
esac
exit $?
but I changed the line echo 55 to: echo 500 > /sys/class/backlight/nvidia_backlight/brightness because my driver is nvidia
Set executable permissions on /etc/pm/sleep.d/00-displayfix:
$ sudo chmod +x /etc/pm/sleep.d/00-displayfix
and after restart everything should work perfect ! :P[/font][/size][/color]
you can press F2 immediately after reboot. It will take you to the system BIOS and display a menu of system options etc http://www.247mobilenews.com/computers-2