The first time a secondary display/projector is connected to my laptop, it is detected and works in mirrored mode. However, once I open System Settings > Displays, the seconday display gets disabled. Loging out and rebooting doesn't solve the problem. At least not right away. A few reboots later secondary display starts working again. Occasioally I'm able to use Fn+F4 to switch between different modes (mirrored, extended), but it usually doesn't last long. As soon as System Settings is activated, the secondary display is disable and no longer detected.
Additional clues:
1) If I leave a display plugged in and reboot, it is activated on login screen, but shuts off as soon as I login. Pressing 'Detect Displays' button is Displays settings does not bring it back.
2)
Every time I open System Settings (even without external displayed plugged in) there is a short lag and even the moust stops moving for about a second. The following shows up in the log:
Oct 28 11:34:12 hostname kernel: [ 649.193034] [drm] probing gen 2 caps for device 8086:9c18 = 5323c42/0
Oct 28 11:34:12 hostname kernel: [ 649.193038] [drm] PCIE gen 2 link speeds already enabled
Oct 28 11:34:12 hostname kernel: [ 649.197195] [drm] PCIE GART of 1024M enabled (table at 0x0000000000276000).
Oct 28 11:34:12 hostname kernel: [ 649.197453] radeon 0000:03:00.0: WB enabled
Oct 28 11:34:12 hostname kernel: [ 649.197455] radeon 0000:03:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff880432d0cc00
Oct 28 11:34:12 hostname kernel: [ 649.197457] radeon 0000:03:00.0: fence driver on ring 1 use gpu addr 0x0000000040000c04 and cpu addr 0xffff880432d0cc04
Oct 28 11:34:12 hostname kernel: [ 649.197458] radeon 0000:03:00.0: fence driver on ring 2 use gpu addr 0x0000000040000c08 and cpu addr 0xffff880432d0cc08
Oct 28 11:34:12 hostname kernel: [ 649.197459] radeon 0000:03:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff880432d0cc0c
Oct 28 11:34:12 hostname kernel: [ 649.197460] radeon 0000:03:00.0: fence driver on ring 4 use gpu addr 0x0000000040000c10 and cpu addr 0xffff880432d0cc10
Oct 28 11:34:12 hostname kernel: [ 649.198991] radeon 0000:03:00.0: fence driver on ring 5 use gpu addr 0x0000000000075a18 and cpu addr 0xffffc90012535a18
Oct 28 11:34:12 hostname kernel: [ 649.388989] [drm] ring test on 0 succeeded in 1 usecs
Oct 28 11:34:12 hostname kernel: [ 649.388994] [drm] ring test on 1 succeeded in 1 usecs
Oct 28 11:34:12 hostname kernel: [ 649.388998] [drm] ring test on 2 succeeded in 1 usecs
Oct 28 11:34:12 hostname kernel: [ 649.389009] [drm] ring test on 3 succeeded in 2 usecs
Oct 28 11:34:12 hostname kernel: [ 649.389016] [drm] ring test on 4 succeeded in 1 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574547] [drm] ring test on 5 succeeded in 2 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574553] [drm] UVD initialized successfully.
Oct 28 11:34:12 hostname kernel: [ 649.574583] [drm] ib test on ring 0 succeeded in 0 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574610] [drm] ib test on ring 1 succeeded in 0 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574637] [drm] ib test on ring 2 succeeded in 0 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574664] [drm] ib test on ring 3 succeeded in 0 usecs
Oct 28 11:34:12 hostname kernel: [ 649.574692] [drm] ib test on ring 4 succeeded in 0 usecs
Oct 28 11:34:13 hostname kernel: [ 649.725287] [drm] ib test on ring 5 succeeded
3)
Some plugging and unplugging of the display occasionally shows the same messages in the log followed by the following:
Oct 28 11:34:13 hostname kernel: [ 649.734010] snd_hda_intel 0000:03:00.1: Enabling via VGA-switcheroo
Oct 28 11:34:13 hostname kernel: [ 649.734117] snd_hda_intel 0000:03:00.1: irq 70 for MSI/MSI-X
Oct 28 11:34:18 hostname kernel: [ 654.876455] snd_hda_intel 0000:03:00.1: Disabling via VGA-switcheroo
Oct 28 11:34:18 hostname kernel: [ 654.908444] snd_hda_intel 0000:03:00.1: Cannot lock devices!
ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: xorg 1:7.7+7ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-23.31-generic 3.16.4
Uname: Linux 3.16.0-23-generic x86_64
.tmp.unity.support.test.0:
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Oct 28 11:26:19 2014
DistUpgraded: 2014-10-24 11:32:59,179 DEBUG enabling apt cron job
DistroCodename: utopic
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 0b) (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device [103c:198f]
Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M] [1002:6601] (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device [103c:1990]
InstallationDate: Installed on 2014-10-06 (22 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Hewlett-Packard HP EliteBook 840 G1
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-23-generic.efi.signed root=UUID=e9a30923-65a7-4f5d-90ad-c34a241f1c73 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to utopic on 2014-10-24 (3 days ago)
dmi.bios.date: 10/09/2013
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: L71 Ver. 01.04
dmi.board.name: 198F
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 15.50
dmi.chassis.asset.tag: CNU347DHK4
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvrL71Ver.01.04:bd10/09/2013:svnHewlett-Packard:pnHPEliteBook840G1:pvrA3009DD10303:rvnHewlett-Packard:rn198F:rvrKBCVersion15.50:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP EliteBook 840 G1
dmi.product.version: A3009DD10303
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1
version.ia32-libs: ia32-libs 20090808ubuntu36
version.libdrm2: libdrm2 2.4.56-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.3.0-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.3.0-0ubuntu3
version.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.0-2ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.914-1~exp1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2
xserver.bootTime: Tue Oct 28 11:23:31 2014
xserver.configfile: default
xserver.errors: RADEON(G0): [XvMC] Failed to initialize extension.
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
product id 4669
vendor AUO
xserver.version: 2:1.16.0-1ubuntu1
I can consistently "revive" the second display by unplugging it, going to stand by, resuming the laptop, and finally plugging the display again. It works and I can switch between different modes even through setting, but at some point if I open Displays settings it gets disabled as described above.