On Lenovo Thinkpad Edge E330, the screen backlight flickers badly.

[Mark]

Behavior is the same on Ubuntu 14.04 -- 15.04.

Steps were taken according to this: https://wiki.ubuntu.com/Kernel/Debugging/Backlight

With acpi_backlight=vendor, the flicker stops, and the brightness control doesn't work.
However,
    echo 8 > /sys/class/backlight/intel_backlight/brightness
dims the screen.

thinkpad-acpi.brightness_enable = 1 does nothing.

Old workaround: If no changes are made to boot options, and
    echo 4437 > /sys/class/backlight/intel_backlight/brightness
is done, the flicker stops and the GUI control / acpi_video0 works, but causes flicker again.

Workaround 2: Kernel parameters: "thinkpad-acpi.brightness_enable=0 acpi_backlight=vendor" fully fix the bug behavior and retain the brightness control.

Issue: the intel_backlight device should be used, the workaround above disables the other devices, leaving only one, thus no conflicts occur.

Attaching the necessary files.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-26-generic 3.19.0-26.28
ProcVersionSignature: Ubuntu 3.19.0-26.28-generic 3.19.8-ckt4
Uname: Linux 3.19.0-26-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: mark 1391 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Aug 20 11:21:39 2015
HibernationDevice: RESUME=UUID=7a9e1f17-c57b-4e6f-bb0c-0b090b5d1405
InstallationDate: Installed on 2014-08-22 (363 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: LENOVO 3354DGG
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-26-generic root=UUID=b566feb2-5a5c-4573-8782-b78d130dbc45 ro quiet splash acpi_backlight=vendor vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.19.0-26-generic N/A
 linux-backports-modules-3.19.0-26-generic N/A
 linux-firmware 1.143.3
SourcePackage: linux
UpgradeStatus: Upgraded to vivid on 2015-08-20 (0 days ago)
dmi.bios.date: 02/25/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: H3ET72WW(1.09)
dmi.board.asset.tag: Not Available
dmi.board.name: 3354DGG
dmi.board.vendor: LENOVO
dmi.board.version: 0B98409 Std
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrH3ET72WW(1.09):bd02/25/2013:svnLENOVO:pn3354DGG:pvrThinkPadEdgeE330:rvnLENOVO:rn3354DGG:rvr0B98409Std:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 3354DGG
dmi.product.version: ThinkPad Edge E330
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This change was made by a bot.

[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 v4.2 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/v4.2-rc7-unstable/

[Mark (markboldyrev)]

I have found a normal fix/workaround for the bug, which removes the flicker and still keeps the controls working:

Kernel parameters: "thinkpad-acpi.brightness_enable=0 acpi_backlight=vendor"

[Mark (markboldyrev)]

This bug was repeatable on other Linux distros: Fedora, etc.

[Mark (markboldyrev)]

@penalvch, Sorry, I have updated my bios since then, and yes, it still repeated.

[Mark (markboldyrev)]

dmidecode:

H3ET75WW (1.12)

03/03/2015

(But the official utuility says that it is already the latest version)

[Christopher M. Penalver (penalvch)]

Mark is this reproducible on the latest mainline kernel (4.3-rc3)?

[Mark (markboldyrev)]

I just upgraded the kernel on 15.04 to the latest available in the repository.
Though when I reverted the settings to the default, the bug is still reproducible.

[Christopher M. Penalver (penalvch)]

Mark, could you please test the latest upstream kernel available from the very top line at the top of the page from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D (the release names are irrelevant for testing, and please do not test the daily folder)? Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds . This will allow additional upstream developers to examine the issue.

If the latest kernel did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this issue is fixed in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the report description:
kernel-fixed-upstream
kernel-fixed-upstream-X.Y-rcZ

Where X, and Y are the first two numbers of the kernel version, and Z is the release candidate number if it exists.

If the mainline kernel does not fix the issue, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-X.Y-rcZ

Please note, an error to install the kernel does not fit the criteria of kernel-bug-exists-upstream.

Once testing of the latest upstream kernel is complete, please mark this report's Status as Confirmed. Please let us know your results.

Thank you for your understanding.

[Mark (markboldyrev)]

I've tested it with v4.4-rc4-wily, and the bug does not exist, leaving only intel_backlight with the default GRUB configuration (no extra options except "quiet splash").

While installing the upstream kernel, though, there was a warning:
          W: Possible missing firmware /lib/firmware/i915/skl_guc_ver4.bin for module i915

[Mark (markboldyrev)]

Packages that I installed:

linux-image-4.4.0-040400rc4-generic_4.4.0-040400rc4.201512061930_amd64.deb
linux-headers-4.4.0-040400rc4_4.4.0-040400rc4.201512061930_all.deb
linux-headers-4.4.0-040400rc4-generic_4.4.0-040400rc4.201512061930_amd64.deb

[Mark (markboldyrev)]

Also, I downgraded to 4.2.0-19-generic and the bug shows again.

[Mark (markboldyrev)]

(I just reinstalled from scratch to version 15.10 today and the kernel version was the one I noted above)

[Christopher M. Penalver (penalvch)]

Mark, the next step is to fully reverse commit bisect from kernel 4.2 to 4.4-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

[Launchpad Janitor (janitor)]

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