Xorg freeze

[jefcap]

Flicker is occurring in my screen randomly. I've tried to disable the nvidia card and use the internal intel graphic card but issue is present in both cases. Noticed everytime this occur, dmesg logs show:
[ 299.696671] ACPI Warning: _BQC returned an invalid level (20170831/video-640)
[ 1123.616996] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[ 1123.617098] [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared pch fifo underrun on pch transcoder A
[ 1123.617159] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

Please help address this bug.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7.1
ProcVersionSignature: Ubuntu 4.15.0-121.123-generic 4.15.18
Uname: Linux 4.15.0-121-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.9-0ubuntu7.17
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Mon Nov 9 12:49:50 2020
DistUpgraded: 2019-08-24 21:40:09,878 DEBUG icon theme changed, re-reading
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.8, 4.15.0-117-generic, x86_64: installed
 bbswitch, 0.8, 4.15.0-121-generic, x86_64: installed
 nvidia, 390.138, 4.15.0-117-generic, x86_64: installed
 nvidia, 390.138, 4.15.0-121-generic, x86_64: installed
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Dell 2nd Generation Core Processor Family Integrated Graphics Controller [1028:050e]
 NVIDIA Corporation GF108M [GeForce GT 540M] [10de:0df4] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Dell GF108M [GeForce GT 540M] [1028:050e]
InstallationDate: Installed on 2019-01-16 (663 days ago)
InstallationMedia: Ubuntu 16.04.5 LTS "Xenial Xerus" - Release amd64 (20180731)
MachineType: Dell Inc. Dell System XPS L502X
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-121-generic root=UUID=9abc6245-6761-49d4-9926-ab9f9d169abc ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: Upgraded to bionic on 2019-08-25 (442 days ago)
dmi.bios.date: 10/20/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A07
dmi.board.name: 0MY6GN
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: 0.1
dmi.modalias: dmi:bvnDellInc.:bvrA07:bd10/20/2011:svnDellInc.:pnDellSystemXPSL502X:pvr:rvnDellInc.:rn0MY6GN:rvrA00:cvnDellInc.:ct8:cvr0.1:
dmi.product.family: HuronRiver System
dmi.product.name: Dell System XPS L502X
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.13.1+18.04.20180302-0ubuntu1
version.libdrm2: libdrm2 2.4.101-2~18.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.8-0ubuntu1~18.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.0.8-0ubuntu1~18.04.1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4.7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.5-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[Daniel van Vugt (vanvugt)]

The log messages you mention are covered by bug 1550779. So that might be the main issue here. But just in case you're experiencing a crash as well, please try these steps:

https://wiki.ubuntu.com/Bugs/Responses#Missing_a_crash_report_or_having_a_.crash_attachment