Comment 0 for bug 1579481

Since I've upgraded 15.10 to 16.04 my external monitor is not working anymore. Whether I plug it directly into the DVI port of my laptop ("HP EliteBook 840 G1") or whether I plug it into the DVI or VGA port of my docking station "HP 2013 UltraSlim-Dockingstation" I get the following error in "/var/log/syslog":
...
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.377223] radeon 0000:03:00.0: VCE init error (-110).
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
...

I tried as well a fresh 16.04 install but this still did not help.
The full log related to plugging in an external monitor is:
...
May 4 19:20:16 hp-elitebook-840-g1--s0-v2 kernel: [ 62.573716] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
May 4 19:20:16 hp-elitebook-840-g1--s0-v2 kernel: [ 62.578032] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
May 4 19:20:16 hp-elitebook-840-g1--s0-v2 kernel: [ 62.578106] acpi PNP0501:00: Still not present
May 4 19:20:16 hp-elitebook-840-g1--s0-v2 kernel: [ 62.578184] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.267945] [drm] probing gen 2 caps for device 8086:9c18 = 5323c42/0
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.267950] [drm] PCIE gen 2 link speeds already enabled
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275081] [drm] PCIE GART of 2048M enabled (table at 0x00000000002E8000).
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275187] radeon 0000:03:00.0: WB enabled
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275190] radeon 0000:03:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff880434a83c00
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275191] radeon 0000:03:00.0: fence driver on ring 1 use gpu addr 0x0000000040000c04 and cpu addr 0xffff880434a83c04
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275192] radeon 0000:03:00.0: fence driver on ring 2 use gpu addr 0x0000000040000c08 and cpu addr 0xffff880434a83c08
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275194] radeon 0000:03:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff880434a83c0c
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.275195] radeon 0000:03:00.0: fence driver on ring 4 use gpu addr 0x0000000040000c10 and cpu addr 0xffff880434a83c10
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.276738] radeon 0000:03:00.0: fence driver on ring 5 use gpu addr 0x0000000000075a18 and cpu addr 0xffffc90002835a18
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.377223] radeon 0000:03:00.0: VCE init error (-110).
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.612628] [drm] ring test on 0 succeeded in 1 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.612635] [drm] ring test on 1 succeeded in 1 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.612640] [drm] ring test on 2 succeeded in 1 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.612650] [drm] ring test on 3 succeeded in 5 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.612658] [drm] ring test on 4 succeeded in 5 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788345] [drm] ring test on 5 succeeded in 2 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788352] [drm] UVD initialized successfully.
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788388] [drm] ib test on ring 0 succeeded in 0 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788421] [drm] ib test on ring 1 succeeded in 0 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788453] [drm] ib test on ring 2 succeeded in 0 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788483] [drm] ib test on ring 3 succeeded in 0 usecs
May 4 19:20:17 hp-elitebook-840-g1--s0-v2 kernel: [ 63.788514] [drm] ib test on ring 4 succeeded in 0 usecs
May 4 19:20:18 hp-elitebook-840-g1--s0-v2 kernel: [ 64.437532] [drm] ib test on ring 5 succeeded
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 tried as well upgrading to the latest kernel as described here:
https://wiki.ubuntu.com/KernelMainlineBuilds - latest v4.6 kernel[0]
But this did not help either.

Some further details:

# lspci -k | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b)
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M] (rev ff)

# xrandr --listproviders
Providers: number : 3
Provider 0: id: 0x6d cap: 0x9, Source Output, Sink Offload crtcs: 4 outputs: 6 associated providers: 2 name:Intel
Provider 1: id: 0x43 cap: 0x6, Sink Output, Source Offload crtcs: 2 outputs: 2 associated providers: 2 name:OLAND @ pci:0000:03:00.0
Provider 2: id: 0x43 cap: 0x6, Sink Output, Source Offload crtcs: 2 outputs: 2 associated providers: 2 name:OLAND @ pci:0000:03:00.0

This bug could be related to: "https://bugzilla.redhat.com/show_bug.cgi?id=1262649" but I could nowhere find any answers when it will be fixed or what is the root cause.