Random display flickering on Kernel 4.8 with dual-screen

[Rocko]

The update to linux-image 4.8.0-15-generic has caused both my laptop screen and external monitor screen to flicker at random intervals on my Skylake laptop, making the desktop annoyingly unusable at times. This issue is not present in the 4.7 or earlier kernels.

Upstream is aware of the issue: see https://bugs.freedesktop.org/show_bug.cgi?id=97450.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: linux-image-4.8.0-15-generic 4.8.0-15.16
ProcVersionSignature: Ubuntu 4.8.0-15.16-generic 4.8.0-rc7
Uname: Linux 4.8.0-15-generic x86_64
ApportVersion: 2.20.3-0ubuntu7
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: rocko 4715 F.... pulseaudio
CurrentDesktop: Unity
Date: Sat Sep 24 07:29:44 2016
HibernationDevice: RESUME=UUID=deb8a0cb-a8a4-4ef6-a09d-7035635c87b7
InstallationDate: Installed on 2016-07-04 (81 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
JournalErrors:
 Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
       Users in the 'systemd-journal' group can see all messages. Pass -q to
       turn off this notice.
 No journal files were opened due to insufficient permissions.
MachineType: Dell Inc. XPS 15 9550
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.8.0-15-generic root=UUID=8de7ebec-48db-48b6-9eb9-fafdee4eb7d6 ro rootflags=subvol=@ quiet splash nogpumanager vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.8.0-15-generic N/A
 linux-backports-modules-4.8.0-15-generic N/A
 linux-firmware 1.161
SourcePackage: linux
UpgradeStatus: Upgraded to yakkety on 2016-07-24 (61 days ago)
WifiSyslog:

dmi.bios.date: 04/07/2016
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 01.02.00
dmi.board.name: 0N7TVV
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr01.02.00:bd04/07/2016:svnDellInc.:pnXPS159550:pvr:rvnDellInc.:rn0N7TVV:rvrA01:cvnDellInc.:ct9:cvr:
dmi.product.name: XPS 15 9550
dmi.sys.vendor: Dell Inc.

[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 v4.8 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/v4.8

[Rocko (rockorequin)]

It's not fixed in the 4.8.0-generic kernel. Additionally, that kernel shows flickering artefact windows when using two monitors, as reported here: https://bugs.freedesktop.org/show_bug.cgi?id=97596

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1626935, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Rocko (rockorequin)]

This is *not* a duplicate of bug #1626935. For a start, it occurs whether the monitor is plugged in at reboot or not, and it refers to a different kind of flickering. I believe I've also seen the flickering referred to in that bug, and it's a constant flickering of part or all of the screen, whereas the flickering mentioned here is where the entire laptop screen goes black temporarily, for half a second or sometimes longer, and then returns to normal.

[Rocko (rockorequin)]

On the bright side, upstream has ameliorated this issue considerably in drm-intel-nightly and the vanilla 4.9-rc1 kernels.

So far the upstream bug has suggested two patches for kernel 4.8.x that reduce the flickering - with those patches, it only occurs a few times a day for me instead of every few seconds or minutes. Maybe we could cherry-pick those patches?

[Antonis Pappas (bigfatpugsley)]

This bug still hasn't been fixed 7 months later. I just switched to the hwe kernel of 16.04 and I am likewise affected.

This may have been mentioned in upstream but the flickering happens only when framebuffer hasn't changed. If you constantly move your mouse, it'll stop.