[Lenovo IdeaPad y510p] Brightness settings do not affect the actual display brightness

[Travis Whitehead]

When I press Fn+Up/Down on my keyboard (the brightness adjust hotkey), the brightness settings the slider moves, however the actual brightness of my laptop display remains the same.

As per https://wiki.ubuntu.com/Kernel/Debugging/Backlight, I have attached the output of several commands as debugging information.

Using the kernel parameter acpi_backlight=vendor, I can no longer adjust the brightness slider with my keyboard hotkey Fn+Up/Down Arrow, and when I go to System Settings -> Brightness & Lock, the brightness slider is no longer present.

The kernel paramater video.use_bios_initial_backlight=0 appears to make no difference, as I can move the brightness slider and it still has no effect.

The kernel paramater video.use_native_backlight=1 also has no noticeable effect.

When booting with the latest mainline kernel (v3.15-rc5-utopic), the issue persists.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-24-generic 3.13.0-24.47
ProcVersionSignature: Ubuntu 3.13.0-24.47-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/controlC1: travis 1559 F.... pulseaudio
 /dev/snd/controlC0: travis 1559 F.... pulseaudio
CurrentDesktop: Unity
Date: Fri May 16 17:55:54 2014
HibernationDevice: RESUME=UUID=85b9a9be-afa0-404e-8b11-c98f93fa4366
InstallationDate: Installed on 2014-05-14 (2 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
MachineType: LENOVO 20217
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic.efi.signed root=UUID=108a3bcd-f7e8-46e6-b5b8-1c1c0fb22903 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 1.127.2
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/18/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 74CN44WW(V3.05)
dmi.board.asset.tag: No Asset Tag
dmi.board.name: VIQY0Y1
dmi.board.vendor: LENOVO
dmi.board.version: 31900058STD
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo IdeaPad Y510P
dmi.modalias: dmi:bvnLENOVO:bvr74CN44WW(V3.05):bd09/18/2013:svnLENOVO:pn20217:pvrLenovoIdeaPadY510P:rvnLENOVO:rnVIQY0Y1:rvr31900058STD:cvnLENOVO:ct10:cvrLenovoIdeaPadY510P:
dmi.product.name: 20217
dmi.product.version: Lenovo IdeaPad Y510P
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This change was made by a bot.

[Travis Whitehead (travis-whitellama-g)]

ls /sys/class/backlight > backlight

[Travis Whitehead (travis-whitellama-g)]

grep -r . /proc/acpi > acpi

[Travis Whitehead (travis-whitellama-g)]

sudo acpidump -o acpidump.txt

[Travis Whitehead (travis-whitellama-g)]

acpixtract acpidump.txt
iasl -d DSDT.dat

[Travis Whitehead (travis-whitellama-g)]

sudo fwts > fwts

[Travis Whitehead (travis-whitellama-g)]

sudo fwts method > fwts_method

[Travis Whitehead (travis-whitellama-g)]

dmesg | grep 'ACPI: Video' > video

[Travis Whitehead (travis-whitellama-g)]

sudo dmidecode > dmidecode.log

[Travis Whitehead (travis-whitellama-g)]

cat /proc/version > version

[Travis Whitehead (travis-whitellama-g)]

With the kernel paramater acpi_backlight=vendor:
ls /sys/class/backlight > vendorbacklight

[Joseph Salisbury (jsalisbury)]

This issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report[0]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug.

Please follow the instructions on the wiki page[0]. The first step is to email the appropriate mailing list. If no response is received, then a bug may be opened on bugzilla.kernel.org.

Once this bug is reported upstream, please add the tag: 'kernel-bug-reported-upstream'.

[0] https://wiki.ubuntu.com/Bugs/Upstream/kernel

[Travis Whitehead (travis-whitellama-g)]

I'm in the process of preparing my information now, but had a question regarding:

"[7.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant):
While booted into the newest upstream mainline kernel only, execute the following via a terminal, and paste the results:
ls /proc ".

I'm unsure as to what I could find in /proc which would qualify as relevant, as the backlight interface exists in /sys/class/backlight. Would it be sufficient for me to leave that field blank, knowing I'll be including all of the information from this report? The output of "ls /proc" alone seems useless without delving into the contents of files/directories, but I could be mistaken. Should I include it anyways?

Thank you for your assistance.