Brightness not working on an HP Pavilion Dv6 with a ATI Radeon HD6770M

Solution 1:

To get working brightness key. try following

press Alt+f2 , execute gksudo gedit /etc/default/grub

Change this line

GRUB_CMLINE_LINUX_DEFAULT="quiet splash"  

to something like below

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Open a terminal by Alt+ctrl +T, Execute sudo update-grub and reboot . See if brightness keys are working.


If the above is not working set a fixed value for brightness. To do so,

Open a terminal by pressing Alt+ctrl+T.

Type ls /sys/class/backlight/*/brightness, copy the outputs to a separate text file

The possibility is there will be two paths,try the following for each path and replace accordingly

example paths will be like

/sys/class/backlight/acpi_video0/brightness

Run following commands in terminal,

  1. For the above path Get the maximum brightness:

    cat  /sys/class/backlight/acpi_video0/max_brightness`
    

Try a lower value to set the brightness, say output is 16 so I will try with half of it

echo 8 | sudo tee  /sys/class/backlight/acpi_video0/brightness

If this works, make this happen in each login automatically by doing the following

sudo gedit /etc/rc.local

Enter this line just before exit 0. It should look like

echo YOUR_VALUE_HERE > /sys/class/backlight/acpi_video0/brightness
exit 0

Also you can try with xdotool Install xdotool