16.04 -> AMD APU via VGA gives blank screen

[R1dO]

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.

[Brad Figg (brad-figg)]

This change was made by a bot.

[R. Becke (subscribe-becke)]

I've the same issue on my "HP EliteBook 840 G1" when I dock my laptop to my "HP 2013 UltraSlim-Dockingstation" I get the following error in "/var/log/syslog":

...
May 4 19:20:18 hp-elitebook-840-g1--s0-v2 kernel: [ 64.811603] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery reached max voltage
May 4 19:20:18 hp-elitebook-840-g1--s0-v2 kernel: [ 64.811619] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
May 4 19:20:18 hp-elitebook-840-g1--s0-v2 kernel: [ 65.062599] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery reached max voltage
May 4 19:20:18 hp-elitebook-840-g1--s0-v2 kernel: [ 65.062614] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
...

I think this bug is related to: https://bugs.freedesktop.org/show_bug.cgi?id=76490
And I think the kernel fix is available: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0e5585dc870af947fab2af96a88c2d8b4270247c

The question is when will this kernel be available in 16.04?

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.6 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6-rc6-wily/

[R1dO (r-den-ouden)]

Dear Joseph,

In response to your questions:
The issue started after an upgrade from 15.10 to 16.04.
The prior version of the kernel without the problem was the one from 15.10 (4.2.0-35)

I will try to test as soon as possible.

Some additional observations regarding this bug.
* It is also present in the installation iso.
* Booting via recovery mode partially fixes/circumvent it. Although it only allows a single and reduced display resolution (1024x768).

[R. Becke (subscribe-becke)]

The same happened to me. I did the upgrade 15.10->16.04 while my laptop was docked into the "HP 2013 UltraSlim-Dockingstation" and at some point during the upgrade my screen went black and so I decided to reboot. And from this point on I could not get my 16.04 system working anymore so I decided to do a 16.04 installation from scratch. Now I can at least work on my laptop standalone but as soon as I try to dock I get the exception in syslog shown above. The weird thing is that in the Display Manager dialog my external Acer Monitor is detected but no output gets displayed.
One further "famous" error I get in syslog is: "radeon 0000:03:00.0: VCE init error (-110)" - so hopefully this gets solved as well with the upgrade.
Will try the kernel upgrade asap.

[R. Becke (subscribe-becke)]

I've installed the latest kernel:
Linux version 4.6.0-040600rc6-generic (kernel@gloin) (gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2) ) #201605012031 SMP Mon May 2 00:33:26 UTC 2016

But the issue is still the same and I still get:
...
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052343] radeon 0000:03:00.0: WB enabled
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052346] radeon 0000:03:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff88043499bc00
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052347] radeon 0000:03:00.0: fence driver on ring 1 use gpu addr 0x0000000040000c04 and cpu addr 0xffff88043499bc04
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052348] radeon 0000:03:00.0: fence driver on ring 2 use gpu addr 0x0000000040000c08 and cpu addr 0xffff88043499bc08
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052350] radeon 0000:03:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff88043499bc0c
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.052351] radeon 0000:03:00.0: fence driver on ring 4 use gpu addr 0x0000000040000c10 and cpu addr 0xffff88043499bc10
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.053893] radeon 0000:03:00.0: fence driver on ring 5 use gpu addr 0x0000000000075a18 and cpu addr 0xffffc90003035a18
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.154397] radeon 0000:03:00.0: VCE init error (-110).
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.388497] [drm] ring test on 0 succeeded in 1 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.388504] [drm] ring test on 1 succeeded in 1 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.388509] [drm] ring test on 2 succeeded in 1 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.388518] [drm] ring test on 3 succeeded in 5 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.388525] [drm] ring test on 4 succeeded in 4 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564268] [drm] ring test on 5 succeeded in 2 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564274] [drm] UVD initialized successfully.
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564310] [drm] ib test on ring 0 succeeded in 0 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564341] [drm] ib test on ring 1 succeeded in 0 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564372] [drm] ib test on ring 2 succeeded in 0 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564401] [drm] ib test on ring 3 succeeded in 0 usecs
May 7 09:26:32 hp-elitebook-840-g1--s0-v2 kernel: [ 82.564430] [drm] ib test on ring 4 succeeded in 0 usecs
May 7 09:26:33 hp-elitebook-840-g1--s0-v2 kernel: [ 83.212279] [drm] ib test on ring 5 succeeded
May 7 09:26:33 hp-elitebook-840-g1--s0-v2 kernel: [ 83.594507] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery reached max voltage
May 7 09:26:33 hp-elitebook-840-g1--s0-v2 kernel: [ 83.594523] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
May 7 09:26:33 hp-elite...

[R1dO (r-den-ouden)]

@ R.Becke

I only did the update, nothing else.
The system only has an APU, no discrete card.
lspci output can be found in post #2

I do want to point out that your system has an additional error, which i can't remember to have seen on my system:
"VCE init error (-110)"
Perhaps you have a slightly different bug on your hands. If so it is probably smarter to open up a separate bug report, so it gets the attention it deserves.

[Aaron Peromsik (aperomsik)]

As I mentioned on 1579481: The commit below (also from upstream) fixes this for me. Hadn't noticed the one mentioned above... I only cherry-picked this one on top of current xenial git source. Would be nice to see this commit find its way into official Xenial kernels.

https://github.com/torvalds/linux/commit/c8213a638f65bf487c10593c216525952cca3690

[didier Belot (electrolinux)]

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.

[didier Belot (electrolinux)]

And here is the second

[Joseph Salisbury (jsalisbury)]

This fix for this bug was cc'd to upstream stable. The fix should make it's way into Xenial through the normal stable updates.

[madbiologist (me-again)]

The abovementioned fix is now in Xenial. Does this issue still occur with the latest Xenial 4.4.0-45.66 kernel?

[R1dO (r-den-ouden)]

Had to dug up my old monitor to check.

The system is capable of booting to the login screen.
Hence the issue seems to be fixed in: Xenial 4.4.0-45.66 kernel