8086:0046 [Acer Aspire 5742] Screen brightness not working

[Merlijn Sebrechts]

My laptop does not respond to the screen brightness control after default Ubuntu install. The following workaround worked: http://askubuntu.com/a/450594
It adds a config file to /usr/share/X11/xorg.conf.d/

adding acpi_backlight=vendor to boot params did nothing
adding acpi_osi=Linux to boot params only fixed the keyboard shortcuts, but the screen indicator and the brightness settings dialog stopped working.

Please let me know if this is not the right package, or if you need more info.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-40-generic 3.13.0-40.69
ProcVersionSignature: Ubuntu 3.13.0-40.69-generic 3.13.11.10
Uname: Linux 3.13.0-40-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: lies 2944 F.... pulseaudio
CurrentDesktop: Unity
Date: Fri Dec 5 12:06:41 2014
HibernationDevice: RESUME=UUID=36715a89-8cd7-40cd-8d29-94f983036914
InstallationDate: Installed on 2014-11-23 (11 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
Lsusb:
 Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 003: ID 04f2:b1d8 Chicony Electronics Co., Ltd
 Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Acer Aspire 5742
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-40-generic root=UUID=1bc3ee22-b016-4fcc-9668-30363b56faa9 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-40-generic N/A
 linux-backports-modules-3.13.0-40-generic N/A
 linux-firmware 1.127.10
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/11/2010
dmi.bios.vendor: Acer
dmi.bios.version: V1.04
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Aspire 5742
dmi.board.vendor: Acer
dmi.board.version: V1.04
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.04
dmi.modalias: dmi:bvnAcer:bvrV1.04:bd08/11/2010:svnAcer:pnAspire5742:pvrV1.04:rvnAcer:rnAspire5742:rvrV1.04:cvnAcer:ct10:cvrV1.04:
dmi.product.name: Aspire 5742
dmi.product.version: V1.04
dmi.sys.vendor: Acer

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue occur in a previous version of Ubuntu, or is this a new issue?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.18 kernel[0].

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/v3.18-rc7-vivid/

[Merlijn Sebrechts (merlijn-sebrechts)]

removing the workaround (intel.conf file in /usr/share/X11/xorg.conf.d/) and booting with the latest vivid kernel (3.18.0-031800rc7-generic #201411302035) did not fix the problem.

Can someone explain me why the workaround works? Is the brightness normally handled by the kernel and does my workaround tell the intel driver to handle it?

Kind regards.

[Merlijn Sebrechts (merlijn-sebrechts)]

This is the first version of Ubuntu I installed. I do not know if this is a regression.

[Merlijn Sebrechts (merlijn-sebrechts)]

Thanks. I updated my bios using freedos (which was surprisingly easy to do!).

sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
V1.30
08/13/2012

This does not fix the problem. If I restart my laptop without the workaround, the effect is still the same. When I change brightness, I see the slider changing, but the brightness stays the same.

[Merlijn Sebrechts (merlijn-sebrechts)]

http://marc.info/?l=linux-acpi&m=141812936311813&w=2

Is this ok?

[penalvch (penalvch)]

Merlijn Sebrechts, I noticed two issues:
1) You didn't you the latest mainline kernel (now 3.18). I just updated the article to help mitigate this in the future.
2) You posted some forum link as a workaround. As the article advised, please do not make people dumpster dive through forums. Instead, just post the actual workaround click-for-click in the e-mail proper.

[Merlijn Sebrechts (merlijn-sebrechts)]

Hi Christopher. Apparently the problem is now fixed in the mainline kernel. Even if I test it now with the 3.18 rc7 kernel, it is fixed. The problem is still there if I use the 3.14 kernel, however.

I do not know how this happened. I suspect that after upgrading the bios, I did not check with the 3.18 kernel, and the combination of new bios + new kernel fixed it...

1) Do I email the acpi mailinglist to let them know the problem is fixed?
2) Will this fix ever be backported to the trusty kernel?

[penalvch (penalvch)]

Merlijn Sebrechts, no need to further e-mail any mailing list at this time. Anyone who is interested will look at the downstream report.

Despite this, the next step is to fully reverse commit bisect from kernel 3.14 to 3.18-rc7 in order to identify the last bad commit, followed immediately by the first good one. Once this commit has been identified, then it may be reviewed as a candidate for backporting into your release. Could you please do this following https://wiki.ubuntu.com/Kernel/KernelBisection#How_do_I_reverse_bisect_the_upstream_kernel.3F ? Please note, finding adjacent kernel versions is not fully commit bisecting.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Launchpad Janitor (janitor)]

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