PDA

View Full Version : [SOLVED] I cannot change screen brightness Ubuntu 11.04



gustokonyan
September 26th, 2011, 05:34 AM
Hi,

I just purchased a new laptop, Acer 4830TG. I installed ubuntu 11.04 right away. Problem is no matter how i set screen brightness, it does not work. My laptop keeps on max brightness i think.

Fn key displays the brightness bar changing as i press the left and arrow keys, but the brightness does not change.

I also tried battery preferences as well as Ubuntu tweak, nothing works.


Can anyone please help? Thank you

gustokonyan
September 26th, 2011, 04:01 PM
anyone please...?

Redblade20XX
September 26th, 2011, 04:06 PM
Can you list your graphics card? Do you have it's proprietary driver installed or the Ubuntu defaults?

matt_symes
September 26th, 2011, 04:17 PM
Hi

Open a terminal and type


sudo bash -c "echo -n 50 > /proc/acpi/video/*/LCD/brightness"

Does this change the brightness ?

Type this to put it back if it does.



sudo bash -c "echo -n 100 > /proc/acpi/video/*/LCD/brightness"

Kind regards

gustokonyan
September 26th, 2011, 04:35 PM
Can you list your graphics card? Do you have it's proprietary driver installed or the Ubuntu defaults?

Hi, here's what lspci says


00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:01.0 PCI bridge: Intel Corporation 2nd Generation Core Processor Family PCI Express Root Port (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 6 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 1 (rev b4)
00:1c.1 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 2 (rev b4)
00:1c.2 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 3 (rev b4)
00:1c.3 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 4 (rev b4)
00:1d.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 6 Series Chipset Family 6 port SATA AHCI Controller (rev 04)
00:1f.3 SMBus: Intel Corporation 6 Series Chipset Family SMBus Controller (rev 04)
01:00.0 VGA compatible controller: nVidia Corporation Device 0df4 (rev a1)
02:00.0 Ethernet controller: Atheros Communications Device 1083 (rev c0)
03:00.0 Network controller: Atheros Communications Inc. AR9287 Wireless Network Adapter (PCI-Express) (rev 01)
04:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5209 (rev 01)
04:00.1 SD Host controller: Realtek Semiconductor Co., Ltd. Device 5209 (rev 01)
05:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04)

I did not install any additional drivers (it was prompted though). So i am using ubuntu default drivers

gustokonyan
September 26th, 2011, 04:37 PM
Hi

Open a terminal and type


sudo bash -c "echo -n 50 > /proc/acpi/video/*/LCD/brightness" Does this change the brightness ?

Type this to put it back if it does.



sudo bash -c "echo -n 100 > /proc/acpi/video/*/LCD/brightness" Kind regards

hello, i tried this but gave the following error:

bash: /proc/acpi/video/*/LCD/brightness: No such file or directory

gustokonyan
September 26th, 2011, 04:40 PM
Thank you guys for replying, but i have to go to bed now. it is 30mins to midnight here :)

I will reply back as soon as possible.

Again, thanks!

matt_symes
September 26th, 2011, 04:41 PM
Hi


hello, i tried this but gave the following error:

bash: /proc/acpi/video/*/LCD/brightness: No such file or directory

What is the result of


ls /proc/acpi/video/

Kind regards

gustokonyan
September 26th, 2011, 04:45 PM
It says "No such file or directory".

ls on /proc/acpi says

ac_adapter battery button event wakeup

matt_symes
September 26th, 2011, 04:55 PM
Hi

On my machine (ubuntu 10.04)


matthew@matthew-laptop:/sys/bus/usb$ ls /proc/acpi/
ac_adapter battery button dsdt embedded_controller event fadt fan info power_resource processor sleep thermal_zone video wakeup
matthew@matthew-laptop:/sys/bus/usb$


I can only assume you have a different version of Ubuntu.

Lets try with /sys.


matthew@matthew-laptop:/sys/bus/usb$ sudo bash -c "echo -n 5 > /sys/class/backlight/acpi_video0/brightness"
matthew@matthew-laptop:/sys/bus/usb$ sudo bash -c "echo -n 9 > /sys/class/backlight/acpi_video0/brightness"


You might have to change acpi_video0 if it is different on your machine.

Kind regards

Toz
September 26th, 2011, 06:54 PM
This link: http://ubuntuforums.org/showthread.php?t=1836945 suggests using the acpi_osi=Linux kernel parameter to solve the brightness issue.

gustokonyan
September 27th, 2011, 05:51 PM
Thank you guys for taking your time to help me with this problem. I originally planned to use ubuntu as my primary OS (as i did on my previous lappy) but i do not want to work with max brightness all the time. So I have now set up my system using win7 and installed all the apps i need for work. I seem to enjoy win7 so far.

I will look into fixing this when time permits..


Again thank you all for your help. It is highly appreciated ;)

gustokonyan
September 30th, 2011, 02:45 PM
This link: http://ubuntuforums.org/showthread.php?t=1836945 suggests using the acpi_osi=Linux kernel parameter to solve the brightness issue.

thank you. this solution worked!

Toz
October 1st, 2011, 01:08 AM
Glad to hear it worked. Can you please mark the thread as solved from the Thread Tools link above?

ranger1021994
July 23rd, 2012, 07:22 PM
Hi,

I just purchased a new laptop, Acer 4830TG. I installed ubuntu 11.04 right away. Problem is no matter how i set screen brightness, it does not work. My laptop keeps on max brightness i think.

Fn key displays the brightness bar changing as i press the left and arrow keys, but the brightness does not change.

I also tried battery preferences as well as Ubuntu tweak, nothing works.


Can anyone please help? Thank you


http://wilmor24.wordpress.com/2010/05/11/change-screen-brightness-from-terminal-ubuntu-10-04/

The process maybe same because terminal commands do not change with new releases

Toz
July 23rd, 2012, 08:07 PM
This thread is 10 months old and resolved. Closing.