8086:0166 [Aspire V5-571P] Backlight not adjustable

[RavanH]

On an Acer Aspire V5 with Intel Graphics, backlight control is not working. Both on Ubuntu GNOME 13.10 and 14.04 neither hotkeys or adjusting the applet slider has any effect. Note that the hotkeys Fn+Left and Fn+Right DO result in a moving slider indicator but no actual backlight change.

Following https://wiki.ubuntu.com/Kernel/Debugging/Backlight "Testing for a workaround" here are my findings. More debugging info will be attached later.

TESTING FOR A WORK AROUND

> Reboot with only the kernel parameter acpi_backlight=vendor :
> Make a comment on if you can now alter the backlight with hotkeys or a brightness applet.

No / Yes *

> sudo su
> echo 8 > /sys/class/backlight/intel_backlight/brightness
> Please comment on if the brightness changes.

Yes

> Reboot with just kernel parameter video.use_bios_initial_backlight=0
> and make a comment on if you can now alter the backlight with hotkeys or a brightness applet.

No / No

> If using a v3.13.x+ series kernel, reboot with just kernel parameter video.use_native_backlight=1
> and make a comment on if you can now alter the backlight with hotkeys or a brightness applet.

Yes / Yes *

* please note that there is no brightness applet in Ubuntu GNOME 14.04 but going to the Settings > Screen Brightness & Lock the brightness can now be controlled

BASIC DEBUGGING INFORMATION (all files will be attached later)

$ ls /sys/class/backlight
acpi_video0 intel_backlight

$ dmesg | grep 'ACPI: Video'
[ 2.969975] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)

$ cat /proc/version
Linux version 3.13.0-24-generic (buildd@panlong) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-24-generic 3.13.0-24.46
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ravanhagen 1918 F.... pulseaudio
CurrentDesktop: GNOME
Date: Fri Apr 18 12:03:12 2014
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-04-14 (3 days ago)
InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Daily amd64 (20140406)
MachineType: Acer Aspire V5-571P
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic.efi.signed root=UUID=631fc653-5697-44cb-b877-f6cae0fda9cf ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-24-generic N/A
 linux-backports-modules-3.13.0-24-generic N/A
 linux-firmware 1.127
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/16/2012
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: V2.13
dmi.board.asset.tag: No Asset Tag
dmi.board.name: Aspire V5-571P
dmi.board.vendor: Acer
dmi.board.version: V2.13
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: Acer
dmi.chassis.version: V2.13
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvrV2.13:bd11/16/2012:svnAcer:pnAspireV5-571P:pvrV2.13:rvnAcer:rnAspireV5-571P:rvrV2.13:cvnAcer:ct9:cvrV2.13:
dmi.product.name: Aspire V5-571P
dmi.product.version: V2.13
dmi.sys.vendor: Acer

[Brad Figg (brad-figg)]

This change was made by a bot.

[RavanH (ravanhagen)]

My appoligies:

It turns out I forgot an update-grub after reverting the kernel parameters. Can/should the attached debug files be removed or replaced? Please let me know :)

And please ignore all remarks about the default interface remaining gone. It's back and called acpi_video0 ... Also the hotkeys are working again and the showkey output is:

Fn+Left:
0xe0 0x4c 0xe0 0xcc

Fn+Right:
0xe0 0x54 0xe0 0xd4

[RavanH (ravanhagen)]

Hi Christopher,

Having Windows 8 on dual boot, I decided to pass via Windows to upgrade the BIOS with the exe downloaded from ACER. Boy do I regret that... It did the upgrade but subsequently I could not boot the system anymore! I managed to get into the BIOS with F2 and switch the SecureBoot option back off (apparently switched on during the upgrade) by switching off UEFI, saving the options and rebooting. Then back into BIOS again and switching UEFI on again made SecureBoot remain off (strange!)... But then I only made it to a grub rescue prompt with a message about Unknown filesystem.

Lots of reading on the net on how to 'fix' this, I still could not resolve it from the prompt each attempt failing with some message about reaching end of file unexpectedly when trying to assign vmlinuz-3.13.0-24 to linux.

Finally created a Live USB and followed instructions for BootRepair (took the one for saucy as there is no trusty repo for it yet) which got the system back up. Amazing software that!

Back in Ubuntu, booted with only "quiet splash" boot parameters, I find that the backlight control is failing again as it was before I added video.use_native_backlight=1 to the kernel boot switches.

dmidecode -s bios-version && dmidecode -s bios-release-date
V2.18
06/21/2013

[penalvch (penalvch)]

RavanH, could you please test the latest upstream kernel available (not the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. 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-3.15-rc2

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

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.

[RavanH (ravanhagen)]

Tested 1.13.10, then moved to 1.14.1 and finally 1.15-rc2. All upstream kernels with the same result: needs video.use_native_backlight=1

[RavanH (ravanhagen)]

By the way, I just noticed a (probably) related bug which exists in all kernels and is NOT resolved with video.use_native_backlight=1

The option in the config screen "Screen brightness and lock" (this is a translation, I have Dutch version so not sure how it is called in English) where it says something like "dim screen to save power"... checked or not... power cable connected or not... it does not have any effect.

[penalvch (penalvch)]

RavanH, the issue you are reporting is an upstream one. Could you please report this problem through the appropriate channel by following the instructions _verbatim_ at https://wiki.ubuntu.com/Bugs/Upstream/kernel ?

Please provide a direct URL to your e-mail to the mailing list once you have made it so that it may be tracked.

Thank you for your understanding.