Comment 0 for bug 1450557

On a 1366x768 Broadwell i3-5010U laptop (System76 Lemur lemu4), sometimes after I logout there is strange horizontal wrapping/scrolling corruption at the lightdm login screen plus a fixed vertical wrapping (see attached video).

After the first time that the screen goes wonky, I see this error in dmesg:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

Logging back into to Unity seems to consistently fix the screen corruption after a few seconds.

This doesn't happen every time you logout, but probably happens 1/3 of the time or so. Occasionally I'll also see similar corruption during shutdown right around the time that X stops and Plymouth takes over.

Interestingly, on a Broadwell i3 desktop connected to a 1920x1080 external display via HDMI, I've never encountered this problem. So it might be related to the specific 1366x768 screen resolution or to the embedded display port (eDP).

I filed this bug against the kernel because of the dmesg error from the DRM module... but the problem could just as likely be in xserver-xorg-video-intel.

For what it's worth, I've tried the latest 4.0 mainline build from the kernel PPA as well as the 4.1rc1 mainline build, and this problem still exists with both. I've also tried the slightly updated X packages for 15.04 from the xorg-edgers PPA, and this problem is likewise still present.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-15-generic 3.19.0-15.15
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: oem 1360 F.... pulseaudio
 /dev/snd/controlC0: oem 1360 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Apr 30 10:23:52 2015
HibernationDevice: RESUME=UUID=35ecebc1-3c1c-4a1f-9431-ce62b4803c50
MachineType: System76, Inc. Lemur
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-15-generic root=UUID=395797c2-b33c-46b5-9a64-abfcd6416195 ro acpi_backlight=vendor quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.19.0-15-generic N/A
 linux-backports-modules-3.19.0-15-generic N/A
 linux-firmware 1.143
SourcePackage: linux
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/25/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 5.6.5
dmi.board.asset.tag: Tag 12345
dmi.board.name: Lemur
dmi.board.vendor: System76, Inc.
dmi.board.version: lemu5
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: System76, Inc.
dmi.chassis.version: lemu5
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr5.6.5:bd02/25/2015:svnSystem76,Inc.:pnLemur:pvrlemu5:rvnSystem76,Inc.:rnLemur:rvrlemu5:cvnSystem76,Inc.:ct9:cvrlemu5:
dmi.product.name: Lemur
dmi.product.version: lemu5
dmi.sys.vendor: System76, Inc.