I think there is another bug report very similar to this one, but can't find it for now. I've never been able to use the stock ubuntu 16.04 kernel with my system (00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Trinity [Radeon HD 7480D]) and need to compile a patched kernel each time... Here are the 2 patches that resolve the problem for me.
** Patch added: "(this is 1 of 2)" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1573648/+attachment/4744507/+files/01_drm_radeon_dp.patch -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1573648 Title: 16.04 -> AMD APU via VGA gives blank screen Status in linux package in Ubuntu: Confirmed Bug description: After upgrade to 16.04, the system will only show a blank screen when a monitor is connected to the VGA output. The system itself is able to completely start-up (checked via a ssh login). Starting up using an older kernel (in this case 4.2.0) gives a functional graphical system. Possibly related dmesg lines (when booting 4.4.0): kernel: [ 9.131059] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery reached max voltage kernel: [ 9.131088] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed It might be related to the following kernel post (but i am not entirely sure): https://lists.freedesktop.org/archives/dri-devel/2016-March/102222.html ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: linux-image-4.4.0-21-generic 4.4.0-21.37 ProcVersionSignature: Ubuntu 4.2.0-35.40-generic 4.2.8-ckt5 Uname: Linux 4.2.0-35-generic x86_64 ApportVersion: 2.20.1-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: rene 2014 F.... pulseaudio /dev/snd/controlC0: rene 2014 F.... pulseaudio CurrentDesktop: Unity Date: Fri Apr 22 16:29:44 2016 HibernationDevice: RESUME=UUID=98dbb6ee-ff08-4e9f-b01d-55b2f28c6a1e InstallationDate: Installed on 2015-12-29 (114 days ago) InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021) IwConfig: lo no wireless extensions. enp1s0 no wireless extensions. MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M. ProcFB: 0 radeondrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-35-generic.efi.signed root=/dev/mapper/VGelmo-LVroot ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.2.0-35-generic N/A linux-backports-modules-4.2.0-35-generic N/A linux-firmware 1.157 RfKill: SourcePackage: linux UpgradeStatus: Upgraded to xenial on 2016-04-21 (0 days ago) dmi.bios.date: 12/04/2015 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: P1.90 dmi.board.name: FM2A68M-HD+ dmi.board.vendor: ASRock dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.90:bd12/04/2015:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnFM2A68M-HD+:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.name: To Be Filled By O.E.M. dmi.product.version: To Be Filled By O.E.M. dmi.sys.vendor: To Be Filled By O.E.M. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1573648/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
