the problem is exactly the same at this post :
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/597070
show only on minidisplay.
main screen on if i use nomodeset.
thanks by advence.
Thomas
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-48-generic 4.15.0-48.51
ProcVersionSignature: Ubuntu 4.15.0-48.51-generic 4.15.18
Uname: Linux 4.15.0-48-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: thomas 1361 F.... pulseaudio
/dev/snd/controlC1: thomas 1361 F.... pulseaudio
CurrentDesktop: XFCE
Date: Sat May 11 13:03:11 2019
InstallationDate: Installed on 2019-01-06 (124 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
MachineType: Apple Inc. iMac9,1
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-48-generic root=UUID=c9d75099-dd8b-49cc-aaf7-c944c44a069b ro quiet splash radeon.modeset=1 vt.handoff=1
RelatedPackageVersions:
linux-restricted-modules-4.15.0-48-generic N/A
linux-backports-modules-4.15.0-48-generic N/A
linux-firmware 1.173.5
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/27/09
dmi.bios.vendor: Apple Inc.
dmi.bios.version: IM91.88Z.008D.B08.0904271717
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F2218FA9
dmi.board.vendor: Apple Inc.
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 13
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F2218FA9
dmi.modalias: dmi:bvnAppleInc.:bvrIM91.88Z.008D.B08.0904271717:bd04/27/09:svnAppleInc.:pniMac9,1:pvr1.0:rvnAppleInc.:rnMac-F2218FA9:rvr:cvnAppleInc.:ct13:cvrMac-F2218FA9:
dmi.product.family: Mac
dmi.product.name: iMac9,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
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