A bit of random testing with undocking and docking repeatedly, with sometimes 'killall unity-settings-daemon' to reread monitors.xml and hopefully reset the display mode, shows weird behaviour.
After a docked fresh boot, after undocking i get for xrandr (SNIPs for brevity): Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 174mm 2560x1440 60.00 + 1920x1440 60.00 [SNIP] DP-1 disconnected (normal left inverted right x axis y axis) HDMI-1 disconnected (normal left inverted right x axis y axis) DP-2 disconnected (normal left inverted right x axis y axis) HDMI-2 disconnected (normal left inverted right x axis y axis) DP-3 disconnected (normal left inverted right x axis y axis) HDMI-3 disconnected (normal left inverted right x axis y axis) DP-3-1 connected (normal left inverted right x axis y axis) 1024x768 60.00 800x600 60.32 56.25 848x480 60.00 640x480 59.94 DP-3-2 connected (normal left inverted right x axis y axis) 1024x768 60.00 800x600 60.32 56.25 848x480 60.00 640x480 59.94 DP-3-3 disconnected (normal left inverted right x axis y axis) Redocking and going through a few glitchy stretched display mode changes gets a more promising xrandr: eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 174mm 2560x1440 60.00 + 1920x1440 60.00 [SNIP] DP-1 disconnected (normal left inverted right x axis y axis) HDMI-1 disconnected (normal left inverted right x axis y axis) DP-2 disconnected (normal left inverted right x axis y axis) HDMI-2 disconnected (normal left inverted right x axis y axis) DP-3 disconnected (normal left inverted right x axis y axis) HDMI-3 disconnected (normal left inverted right x axis y axis) DP-3-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 518mm x 324mm 1920x1200 59.95 + 1920x1080 50.00 [SNIP] DP-3-2 connected (normal left inverted right x axis y axis) 1920x1200 59.95 + 1920x1080 50.00 [SNIP] DP-3-3 disconnected (normal left inverted right x axis y axis) But that just means the monitors are advertised in System Settings -> Displays, where I can change their position, resolution, etc. but they stay dark. Here's a few log lines after undocking: Dez 20 16:15:31 talas kernel: [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* failed to enable link training Dez 20 16:15:31 talas kernel: [drm:intel_dp_start_link_train [i915]] *ERROR* failed to start channel equalization Dez 20 16:16:18 talas kernel: [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* failed to enable link training Dez 20 16:16:18 talas kernel: [drm:intel_dp_start_link_train [i915]] *ERROR* failed to start channel equalization Dez 20 16:17:16 talas kernel: [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* failed to enable link training Dez 20 16:17:16 talas kernel: [drm:intel_dp_start_link_train [i915]] *ERROR* failed to start channel equalization After docking and various shenanigans I get: Dez 20 16:29:56 talas kernel: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun Notably the "too many voltage retries" error is missing this time. Again when rebooting everything works fine. Except for un-/redocking of course. -- 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/1651454 Title: [Lenovo Thinkpad T460p] Ultra Dock external displays not detected after suspend/resume cycle Status in linux package in Ubuntu: Confirmed Bug description: The bug is identical to the expired https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1568573 where a new report was requested. This time around with a fresh install of 16.10 amd64 on a Thinkpad T460p and a Lenovo Ultra Dock with two external monitors. The setup does work when freshly booting with the laptop on the dock. Suspending undocked, docking, resuming doesn't light up the external monitors. Neither does just docking awake. The relevant error messages seem to be these: Dec 20 13:21:50 talas kernel: [265391.482117] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up Dec 20 13:21:50 talas kernel: [265391.498583] [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF D idle bit Other relevant bug reports might be: https://bugzilla.redhat.com/show_bug.cgi?id=1316877 https://bbs.archlinux.org/viewtopic.php?id=209791 ProblemType: Bug DistroRelease: Ubuntu 16.10 Package: linux-image-4.8.0-30-generic 4.8.0-30.32 ProcVersionSignature: Ubuntu 4.8.0-30.32-generic 4.8.6 Uname: Linux 4.8.0-30-generic x86_64 ApportVersion: 2.20.3-0ubuntu8.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: donjan 2341 F.... pulseaudio /dev/snd/pcmC1D0p: donjan 2341 F...m pulseaudio /dev/snd/controlC1: donjan 2341 F.... pulseaudio CurrentDesktop: GNOME-Flashback:Unity Date: Tue Dec 20 15:36:08 2016 InstallationDate: Installed on 2016-10-25 (56 days ago) InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2) MachineType: LENOVO 20FXS0Y200 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.8.0-30-generic root=UUID=104820cc-7d87-46d1-a1aa-e650ff221603 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.8.0-30-generic N/A linux-backports-modules-4.8.0-30-generic N/A linux-firmware 1.161 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 09/26/2016 dmi.bios.vendor: LENOVO dmi.bios.version: R07ET71W (2.11 ) dmi.board.asset.tag: Not Available dmi.board.name: 20FXS0Y200 dmi.board.vendor: LENOVO dmi.board.version: Not Defined dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.modalias: dmi:bvnLENOVO:bvrR07ET71W(2.11):bd09/26/2016:svnLENOVO:pn20FXS0Y200:pvrThinkPadT460p:rvnLENOVO:rn20FXS0Y200:rvrNotDefined:cvnLENOVO:ct10:cvrNone: dmi.product.name: 20FXS0Y200 dmi.product.version: ThinkPad T460p dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1651454/+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
