** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Bionic)
Status: New => Fix Committed
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https://bugs.launchpad.net/bugs/1788308
Title:
[Regression] Colour banding appears on Lenovo B50-80 integrated
display
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Bionic:
Fix Committed
Bug description:
The problem affects the integrated display on a Lenovo B50-80
notebook.
Colour banding is visible everywhere on the system, as dithering seems
not to be enabled on this 6bpp display. This issue was not present on
non-HWE Ubuntu 16.04, and it showed up after I upgraded to Ubuntu
18.04. There was already a very similar bug #1749420 that had a fix
released, however, because the make and model of an LCD screen in that
case was different, the quirk added to the kernel did not address the
problem that affects my machine. The cause of this issue is probably
the same, since I have checked that pre-4.8.0-rc2 kernels handled
dithering correctly, and 4.8.0-rc2 and later kernels already had the
bug described. I believe that adding quirk for an another type of
display may fix the problem.
I attached the results of running
sudo get-edid | parse-edid in a file named edid.txt
and
sudo get-edid | edid-decode in a file named edid-decoded.txt.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-32-generic 4.15.0-32.35
ProcVersionSignature: Ubuntu 4.15.0-32.35-generic 4.15.18
Uname: Linux 4.15.0-32-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: me 1245 F.... pulseaudio
/dev/snd/controlC1: me 1245 F.... pulseaudio
Date: Wed Aug 22 00:26:15 2018
HibernationDevice: RESUME=UUID=93b28df5-b453-452b-960d-7173994d778e
InstallationDate: Installed on 2018-08-21 (0 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64
(20180725)
MachineType: LENOVO 80EW
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-32-generic
root=UUID=a1cd5b8c-2707-4840-858b-3ca12517193b ro quiet splash vt.handoff=1
PulseList:
Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not
accessible: Permission denied
No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-4.15.0-32-generic N/A
linux-backports-modules-4.15.0-32-generic N/A
linux-firmware 1.173.1
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/02/2016
dmi.bios.vendor: LENOVO
dmi.bios.version: A8CN54WW(V3.07)
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: Lenovo B50-80
dmi.board.vendor: LENOVO
dmi.board.version: 31900058 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo B50-80
dmi.modalias:
dmi:bvnLENOVO:bvrA8CN54WW(V3.07):bd09/02/2016:svnLENOVO:pn80EW:pvrLenovoB50-80:rvnLENOVO:rnLenovoB50-80:rvr31900058WIN:cvnLENOVO:ct10:cvrLenovoB50-80:
dmi.product.family: IDEAPAD
dmi.product.name: 80EW
dmi.product.version: Lenovo B50-80
dmi.sys.vendor: LENOVO
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