Backlight Bug

[Juanito de los palotes]

Backlight control does not work and there are no entries in /sys/class/backlight

On other linux distributions backlight control works fine and there is an entry in /sys/class/backlight

I attach the files with debugging information.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-51-generic 4.4.0-51.72
ProcVersionSignature: Ubuntu 4.4.0-51.72-generic 4.4.30
Uname: Linux 4.4.0-51-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: zulu 1367 F.... pulseaudio
CurrentDesktop: XFCE
Date: Wed Dec 7 20:03:48 2016
HibernationDevice: RESUME=UUID=471f1492-ab85-4809-b043-1b95ab3d8e28
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 8087:0a2a Intel Corp.
 Bus 001 Device 003: ID 1bcf:0005 Sunplus Innovation Technology Inc. Optical Mouse
 Bus 001 Device 002: ID 04f2:b424 Chicony Electronics Co., Ltd
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: ASUSTeK COMPUTER INC. GL552VW
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-51-generic root=UUID=20bcbace-4432-45d8-bff1-cf7b1b4b7aa3 ro nomodeset quiet splash vt.handoff=7 video.use_bios_initial_backlight=0
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-51-generic N/A
 linux-backports-modules-4.4.0-51-generic N/A
 linux-firmware 1.157.5
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/16/2016
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: GL552VW.218
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: GL552VW
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrGL552VW.218:bd03/16/2016:svnASUSTeKCOMPUTERINC.:pnGL552VW:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnGL552VW:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
dmi.product.name: GL552VW
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.9 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'.

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/v4.9-rc8

[Juanito de los palotes (jjjuuann)]

Hi, thanks for getting back.

This is an almost clean installation of Xubuntu 16.04. I believe that after installation of Xubuntu, the system asked me to update some programs and I did so. I did not notice this bug before those updates, but I didn't test for it either. So I'm not sure if this started to happen after an update, sorry. Maybe I should try a clean install and test the back-light controls before any update?

I will now test the kernel that you suggest and report the results.

Thanks.

[Juanito de los palotes (jjjuuann)]

Tested latest v4.9 kernel, as suggested by Joseph Salisbury. The bug remains exactly the same:
Backlight control does not work and there are no entries in /sys/class/backlight

Apart from that, this kernel makes the PC run slow (at least, a big latency is observed on the screen when typing on moving the mouse). This might not be related to the backlight bug , but I will uninstal the upstream kernel if no more testing is needed with it.

Thanks.

[penalvch (penalvch)]

Juanito de los palotes:
1) To clarify the Bug Description, what other linux distributions did you use specifically (ex. vendor, kernel version, etc.)?
2) Was a WORKAROUND identified following https://wiki.ubuntu.com/Kernel/Debugging/Backlight ?

[Launchpad Janitor (janitor)]

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