8086:0046 [Acer 3820T] Brightness control not working

[Carl Englund]

"Backlight control does not work, but there are entries in /sys/class/backlight."
- Neither fn+left/right nor system tools brightness control works.

WORKAROUND: acpi_backlight=vendor

WORKAROUND: With acpi_osi=Linux I can now control the brightness lever with the keys.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: linux-image-3.5.0-19-generic 3.5.0-19.30
ProcVersionSignature: Ubuntu 3.5.0-19.30-generic 3.5.7
Uname: Linux 3.5.0-19-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.6.1-0ubuntu6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: diskdoc 2728 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Date: Sat Dec 8 01:16:24 2012
EcryptfsInUse: Yes
HibernationDevice: RESUME=UUID=11efe0be-9f52-4ee5-ae6c-7e025de38353
InstallationDate: Installed on 2010-06-07 (914 days ago)
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100427.1)
MachineType: Acer Aspire 3820
MarkForUpload: True
ProcFB:
 0 inteldrmfb
 1 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-19-generic root=UUID=8b7cae99-dae3-4d14-bbd3-24f82a9e0b57 ro quiet splash rootflags=data=writeback acpi_backlight=vendor vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.5.0-19-generic N/A
 linux-backports-modules-3.5.0-19-generic N/A
 linux-firmware 1.95
SourcePackage: linux
UpgradeStatus: Upgraded to quantal on 2012-12-05 (2 days ago)
dmi.bios.date: 10/27/2010
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: V1.19
dmi.board.asset.tag: No Asset Tag
dmi.board.name: JM31_CP
dmi.board.vendor: Acer
dmi.board.version: V1.19
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.19
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrV1.19:bd10/27/2010:svnAcer:pnAspire3820:pvrV1.19:rvnAcer:rnJM31_CP:rvrV1.19:cvnAcer:ct10:cvrV1.19:
dmi.product.name: Aspire 3820
dmi.product.version: V1.19
dmi.sys.vendor: Acer

[Brad Figg (brad-figg)]

This change was made by a bot.

[Carl Englund (englundc)]

Did "echo 8 > /sys/class/backlight/intel_backlight/brightness" as su and it made the screen go a lot darker.

Instead of "acpi_backlight=vendor" I tried "video.use_bios_initial_backlight=0" but it doesn't work.

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.7 kernel[0] (Not a kernel in the daily directory) and install both the linux-image and linux-image-extra .deb packages.

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-raring/

[Carl Englund (englundc)]

Tested the 3.7-raring kernel. The problem remains just as before.

[Carl Englund (englundc)]

After updating to Ubuntu 13.04 Raring with the latest updates, adding "vendor=backlight" does no longer resolve the problem.

I did however see entries in /sys/class/backlight/ and echoing numbers to /sys/class/backlight/intel_backlight/brightness affects the brightness.

After adding also "acpi_osi=Linux" to the boot options I can now controll the brightness lever with the keys.

[penalvch (penalvch)]

Carl Englund, could you please confirm this issue exists with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ . If the issue remains, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

Also, could you please test the latest upstream kernel available following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Please do not test the daily folder, but the one all the way at the bottom. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.11-rc4

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

If you are unable to test the mainline kernel, please comment as to why specifically you were unable to test it and add the following tags:
kernel-unable-to-test-upstream
kernel-unable-to-test-upstream-VERSION-NUMBER

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

[Launchpad Janitor (janitor)]

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