Acer Aspire 5742Z No Screen Brightness Control

[787B]

The screen brightness controls on this laptop do not work in Ubuntu 10.10 with all updates installed to-date.

Pressing the Fn+arrow keys will bring up the brightness notification and indicate a change, but nothing happens. The power control is unable to dim the screen when switching to battery power or when idle.

There are many other bugs in Launchpad for brightness problems with laptops, but none specifically for the Acer Aspire 5742Z. The similar laptops appear to have other problems I don't have, and fixes suggested in those bugs (nomodeset, acpi_backlight=vendo) do not work on the 5742Z.

Log files attached of various systems:
    cat /proc/version_signature > version.log
    dmesg > dmesg.log
    sudo lspci -vnvn > lspci-vnvn.log
    sudo acpidump -o acpidump.txt
    sudo acpidump -o acpidump.txt
    grep -r . /proc/acpi/video >grep-video.txt

[787B (787b)]

Additional testing: Adding "acpi_osi=" (without quotes) with nothing after the equal sign to the GRUB_CMDLINE_LINUX_DEFAULT line in /etc/default/grub makes the brightness keys work complete with 10 levels of brightness. However, the notification no longer works.

Also, connecting and removing the AC adapter does not change the brightness, even though power management is set to do so. Curiously, hitting brightness up key after unplugging the AC adapter drops the brightness to 20%, suggesting the power management tried to set the brightness value, but it didn't actually change the value. The opposite happens when plugging back into AC.

[787B (787b)]

Confirming that the problem still exists with all updates to-date installed.

[Melvin Garcia (virtualspectre8)]

I can confirm this bug. I have the same laptop with Ubuntu 10.10 fully updated and it doesn't work. I tried the fix above but it doesn't work for me.

I installed linux 2.6.37 and the bug persists. I will try using a Natty live session to see if this persists in the latest image.

[Luis Silva (lacsilva)]

This is also true for Natty.

[787B (787b)]

Confirming that the problem still exists with all updates to 2011-03-06 installed. I'll test with Natty alpha 4 this evening.

Melvin, the "acpi_osi= " consistently works for me. Make sure you have a blank space after the equal sign. I put it right after the "splash" in the boot commands.

[787B (787b)]

Confirmed identical behavior on Ubuntu Natty 11.04 apha 4. Even the work-around works. (Though by the looks of it I probably will be switching distributions.)

[Wasif Hasan Baig (baig)]

I have Acer Aspire 5742Z-4685. This problem existed in my ubuntu 10.10 installation and yesterday i updated to Natty beta and this problem is still there.

[Lee Byrd (lairsupport)]

Confirmed under Ubuntu 10.10 fully updated as of 4/16/2011. Model is 5810TZ-4274. Cuts effective battery life in half.

[Rezaur Rahman (refayetbd-h)]

my fn key for brightness control in Acer Aspire 5742z for Ubuntu11.04 dose not work. it shows brightness decreases but there is no effect.

[Barry (barry-walsh)]

I have an Acer Aspire 5750G with the same brightness control problem.
I have a current installation of Ubuntu 11.04

Adding the fix to the grub command line worked.

If you have problems with this, check that you have done an update-grub after changing the command in /etc/default/grub

[Eric (erivas3649)]

I have an Acer Aspire 5741 with Natty fully updated and still i have no backlight control

[Julian Wiedmann (jwiedmann)]

Eric (and anyone else affected):
have you tried following the advice at https://launchpad.net/~kamalmostafa/+archive/linux-kamal-mjgbacklight ?

[Luke Cassar (lukecassar7)]

Hello Everyone, just to confirm,

The new line will be, 'GRUB_CMDLINE_LINUX_DEFAULTacpi_osi= '

and then save and update GRUB?

[penalvch (penalvch)]

787B, thank you for reporting this bug and helping make Ubuntu better. Please execute the following command, as it will automatically gather debugging information, in a terminal:
apport-collect 693942
As well, could you please provide all relevant detail following: https://wiki.ubuntu.com/Kernel/Debugging/Backlight ?

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]