Brightness keys don't work on Acer Aspire 5740

[sashoalm]

I'm reposting here my solution from the launchpad thread, so people having this problem can try the solution. If you have the same laptop and problem try it and post the results:

SOLVED (for my laptop at least - Acer Aspire 5740)

The trick was to add "acpi_osi=" (without the quotation marks) to the GRUB parameters. Setting the parameter to an empty string means that no OS is reported to the BIOS. By default acpi_osi is set to Windows NT. I had previously tried "acpi_osi=Linux" but it didn't work, apparently it had to be an empty string.

The brightness keys work now

I think it might work for other models as well if they have core i3 processors.

[JBud]

Thank you VERY much for this solution... I have been searching for a solution to this issue for a long time, I can confirm that this works on my Aspire 5740.

Cheers,
-Joe

[Quackers]

Is this for Fn+F5 type key combinations or a dedicated brightness button? I am not familiar with your laptop.
Thanks

[JBud]

Is this for Fn+F5 type key combinations or a dedicated brightness button? I am not familiar with your laptop.
Thanks

It solves all of the fn combinations that I know of... fn+f5 for screen options, fn+f6 for turning off the display backlight, fn+f4 for sleep fn+f8 for mute, etc... But the problem I had a huge problem with was fn+left/right for brightness control, and this workaround solved it!

[Quackers]

Ok, thanks for the details

[photographer92]

Hello Im having similar problems except i cant see the screen to change anything!! Its too dark. Im dual booting Windows 7 and Ubuntu 10.04. I have to get very close to the screen and even then its very hard. Acer Aspire 5741 Laptop

[JBud]

Hello Im having similar problems except i cant see the screen to change anything!! Its too dark. Im dual booting Windows 7 and Ubuntu 10.04. I have to get very close to the screen and even then its very hard. Acer Aspire 5741 Laptop

Hi, did you try the above suggestion? (adding 'acpi_osi=' to grub params)

[JBud]

Okay, I found the best solution. The acpi_osi= is an OK workaround, but does not provide the ability for power management to work. So the best solution is as follows:

Step 1)

Make absolutely sure that this will support your system by running this command:

lsmod | grep ^i915

If your output is SIMILAR to:

i915 331519 3

(The i915 MUST show up, the other numbers may vary)
then continue to step 2, otherwise, this patch will not work.

Step 2)

Now you must add the repository for the linux-kamal-mjgbacklight kernel (The patch for intel gma backlights)

Run this command:

sudo add-apt-repository ppa:kamalmostafa/linux-kamal-mjgbacklight

Run the update manager, and install the new kernel (The current version is 2.6.35-24) that appears, it should show that it is from the above repository. (You should also install any other software from the repository, such as the power management, however, I am fairly sure that only the kernel is required for the patch to work.

Before you reboot, open up:
/etc/grub.d/10_linux

Find this line:

args="$4"

Replace it with:

args="acpi_backlight=vendor $4"

Finally run the command:

sudo update-grub

Now reboot, and from grub, select the new kernel, you will now have FULL backlight control.


Ref: https://launchpad.net/~kamalmostafa/...l-mjgbacklight

This worked perfectly for my Acer Aspire 5740

[theMOTHY]

Tried your "best" solution for my Acer Aspire 5740 (no suffix) and I needed, in addition to what you suggested, to change the following line in /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

which disables acpi_video0.

This was listed in your reference website (https://launchpad.net/~kamalmostafa/...l-mjgbacklight) towards the bottom of the page but I must have missed the first few times around.

That being said, thanks JBud, my brightness controls are now working perfectly!

[robertbub]

I have an Aspire 5740-5513 and I tried

• acpi_osi=Linux
• acpi_osi=
• acpi_backlight=vendor

and none of 'em allow either the brightness applet nor the Fn-left/Fn-right keys to work.

I appear to be running 2.6.32-32-generic-pae on Lucid Lynx. The X Windows appears to be

ii  xserver-xorg-video-intel 2:2.11.0-1ubuntu1~xup  Org X server -- Intel i8xx, i9xx display d

Does this mean that I'm out of luck?