How to control Brightness

Question

I didn't install anything myself, but only Ubuntu 12.04 LTS on an Acer 4741g.

I use Fn+left/right to change the brightness, but failed.

How can I control the brightness levels?

Answer 1

Try this:

1. Open a terminal (Ctrl + Alt + T).
2. Then type sudo nano /etc/default/grub. It will ask for your password. Type it in.
3. Around the 11th line, there will be something like: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash". Change it to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
4. Save the file by Ctrl+O followed by Ctrl+X. Then run sudo update-grub in the terminal.
5. Reboot and see if backlight adjustment works. If not, undo the changes you did above, by invoking the text editor as in steps 1 and 2.

Hope it helps.

Works for Acer Aspire v3-571,Acer Aspire v3 571g,Hewlett Packard Bell EasyNote TS,Acer Aspire 4755G,Acer Aspire 5750-6866

Answer 2

OP reported in Revisions 2 & 3 of the question that the following worked for him.

I figured it out from different sites, it fixes backlight.

Run the following command in Terminal:

gksu gedit /etc/default/grub

then change

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX="acpi_osi=Linux"

then save and run:

sudo update-grub 

and then restart the system for changes to take effect.

Answer 3

[Like in richy's, but] I use GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="

(I'm on an Aspire 5750-6866.) It works fine, same control levels I had in Windows.

My brightness used to be stuck at max before I discovered this; I know that feel bro!

(Although brightness levels still reset after a restart/hibernate/shutdown)

Answer 4

I found out a solution that worked with my laptop:

add this to /etc/rc.local:

echo 2 > /sys/class/backlight/acpi_video0/brightness

Answer 5

I had the same problem. I have a Travelmate P633-V and I did this code to fix it.

After installing the scripts my FN-Left and FN-Right are working fine.

The script should work with all intel devices that exposes /sys/class/backlight/intel_backlight

https://github.com/codingtony/acer-brightness-linux-acpi

Answer 6

I got this problem when i upgraded from 11.10 to 12.04. enter this in terminal code:

sudo gedit /etc/default/grub

Check for these lines GRUB_CMDLINE_LINUX_DEFAULT and change it as the below and save it.

After the update the grub

code: sudo update-grub

Code:

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 nomodeset acpi_backlight=vendor"**`
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# 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=640x480

# 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_RECOVERY="true"

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

Answer 7

Try the following:

sudo gedit /etc/default/grub

Then change this line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor" Then in a terminal type sudo update-grub Reboot and see if the problem is solved.

Answer 8

(Defunct) solution for Ubuntu 12.04.1:

Use Add Drivers / Additional Drivers to load Cedar Trail drm driver (closed source).

---

For Ubuntu 12.04.2 (and fully updated 12.04) this issue is resolved by more recent updates. It does not require the proprietary driver.

If you have just done a fresh install of 12.04.2, then you need to update (and re-start) to fix this.

At terminal, type sudo apt-get update && sudo apt-get upgrade and then sudo apt-get dist-upgrade.

---

Update: (28-Apr-2013)

Repeated steps, with fresh install. This did not fix problem.

While the brightness is fixed, any dimness/brightness adjustment (using function keys) does not seem work after this fix ..

Ongoing ...

Answer 9

Most simple and fast way to do this.... Use this command

xrandr --output LVDS1 --brightness 0.5

Set the value in between 0 to 1 like in this case it is 0.5 This works for me Try this !!!