Backlight control not working Dell Insprion Mini 10

[sys64738]

Since my upgrade from Lubuntu 14.04 to 14.10, my backlight controls (hotkeys to increase/decrease brightness) no longer work on my Dell Inspiron Mini 10. With 14.04 and earlier versions there was no problem.

There are entries under /sys/class/backlight. I have also tried booting with acpi_backlight=vendor. After rebooting with that option, there was a dell entry under /sys/class/backlight, but this didn't fix the problem.

Trying to pass brightness values to the files under /sys/class/backlight didn't change brightness either (I believe I tried all of them).

I'll try to add the attachments recommended by https://wiki.ubuntu.com/Kernel/Debugging/Backlight in a moment.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: linux-image-3.16.0-24-generic 3.16.0-24.32
ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
Uname: Linux 3.16.0-24-generic i686
ApportVersion: 2.14.7-0ubuntu8
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: rb706 1823 F.... lxpanel
CRDA: Error: [Errno 2] Datei oder Verzeichnis nicht gefunden: 'iw'
CurrentDesktop: LXDE
Date: Wed Nov 12 20:22:11 2014
HibernationDevice: RESUME=UUID=85e4a4ec-638f-4cac-820e-4f458beed81c
InstallationDate: Installed on 2013-09-16 (422 days ago)
InstallationMedia: Lubuntu 13.04 "Raring Ringtail" - Release i386 (20130423.1)
MachineType: Dell Inc. Inspiron 1010
ProcFB: 0 psbdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-24-generic root=UUID=9116d68a-2def-4507-83f0-9e895e68e835 ro quiet splash vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-3.16.0-24-generic N/A
 linux-backports-modules-3.16.0-24-generic N/A
 linux-firmware 1.138
SourcePackage: linux
UpgradeStatus: Upgraded to utopic on 2014-11-10 (2 days ago)
dmi.bios.date: 07/23/2009
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A07
dmi.board.name: 0R990K
dmi.board.vendor: Dell Inc.
dmi.board.version: A07
dmi.chassis.asset.tag: **********
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A07
dmi.modalias: dmi:bvnDellInc.:bvrA07:bd07/23/2009:svnDellInc.:pnInspiron1010:pvrA07:rvnDellInc.:rn0R990K:rvrA07:cvnDellInc.:ct8:cvrA07:
dmi.product.name: Inspiron 1010
dmi.product.version: A07
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[sys64738 (sys64738)]

I should probably add that the system reacts on the brightness keys (F4/F5) by displaying and changing the brightness bar indicator, only that this has no effect on the actual screen brightness.

[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 v3.18 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-rc4-vivid/

[sys64738 (sys64738)]

I have now installed kernel:

 3.18.0-031800rc4-generic #201411091835 SMP Sun Nov 9 23:58:06 UTC 2014 i686 i686 i686 GNU/Linux

After booting with this kernel, the system was not fully functional (desktop shown, but LXDE start menu and taskbar empty).

However pushing F4/F5 for decreasing/increasing brightness did work. No brightness bar shown, but the brightness changed as you would expect.

I checked /sys/class/backlight and noticed that it didn't have the entry "acpi_video1" which it does have with with the kernel that comes with 14.10. (just in case it may mean something).

[sys64738 (sys64738)]

I just tried again changing the brightness value via the command line, like

echo 15 > /sys/class/backlight/acpi_video0/brightness

echo 1 > /sys/class/backlight/acpi_video0/brightness

and now saw that this did work. Looks like I didn't test this correctly in the first place. So the problem must be on a different level, any suggestions?

[sys64738 (sys64738)]

xbacklight doesn't work either:

xbacklight -set 5
No outputs have backlight property

[sys64738 (sys64738)]

I was brave enough to update the BIOS and got the new version:

Running

  sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

I get:

  A11
  10/27/2009

The system has booted successfully, but the problem with the brightness control is still the same. Setting brightness through /sys/class/backlight/acpi_video0/brightness works, but xbacklight returns an error message and the brightness control keys have no effect.

[penalvch (penalvch)]

sys64738, the next step is to fully reverse commit bisect from kernel 3.16 to 3.18-rc4 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

[sys64738 (sys64738)]

The problem still exists with kernel 3.17.3 and seems to be fixed with 3.18-rc1 (where the system behaviour is the same as described further above for 3.18-rc4).

I have read the wiki articles about bisecting with git (and found all of this quite interesting) and also locally built one kernel version but then decided not to walk through the whole procedure. This is just a netbook which requires a lot of patience for running the builds, and I currently don't have a more powerful Ubuntu machine available for building the kernels.

Also, there is the workaround with writing brightness values to the kernel's file system interface, so I can wait for 15.04.

However, if pre-built kernel packages for the intermediate builds betwen 3.17.3 and 3.18-rc1 were available anywhere, I would try them.

I would also be interested in learning about for what possible reasons the /sys/class/backlight interface works and why the hotkeys don't.

Best Regards

[Launchpad Janitor (janitor)]

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