I have this exact same issue. I have connected two displays (RGB and HDMI cables) I've updated from Ubuntu 18.04 to 18.10. Everything was working correctly in 18.04.
Steps to reproduce: Case 1: 1. Start docked laptop with displays connected in the docking station 2. Undock laptop 3. Redock laptop -> Freeze/black screen Case 2: 1. Start docked laptop without displays connected in the docking station 2. Undock laptop 3. Redock laptop 4. Connect display (RGB or HDMI) in the docking station -> Freeze HW info: Manufacturer: LENOVO Product Name: 20HGS27000 Version: ThinkPad T470s Serial Number: PC0MJA2W BIOS Version: N1WET51W (Release Date: 09/14/2018) System info: $ lsb_release -rd Description: Ubuntu 18.10 Release: 18.10 $ uname -a Linux citadel 4.18.0-10-generic #11-Ubuntu SMP Thu Oct 11 15:13:55 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux Previously installed working versions: Ubuntu: 18.04 Linux kernel: 4.15.0-38-generic Network Manager: 1.10.6-2ubuntu1 Logs: nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:38 citadel kernel: usb 2-4: new SuperSpeed Gen 1 USB device number 5 using xhci_hcd nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: usb 2-4: New USB device found, idVendor=17ef, idProduct=1012, bcdDevice=50.41 nov 02 12:09:39 citadel kernel: usb 2-4: New USB device strings: Mfr=1, Product=2, SerialNumber=0 nov 02 12:09:39 citadel kernel: usb 2-4: Product: Lenovo ThinkPad Dock nov 02 12:09:39 citadel kernel: usb 2-4: Manufacturer: LENOVO nov 02 12:09:39 citadel kernel: hub 2-4:1.0: USB hub found nov 02 12:09:39 citadel kernel: hub 2-4:1.0: 4 ports detected nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: usb 1-4: new high-speed USB device number 12 using xhci_hcd nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: usb 1-4: New USB device found, idVendor=17ef, idProduct=1012, bcdDevice=50.40 nov 02 12:09:39 citadel kernel: usb 1-4: New USB device strings: Mfr=1, Product=2, SerialNumber=0 nov 02 12:09:39 citadel kernel: usb 1-4: Product: Lenovo ThinkPad Dock nov 02 12:09:39 citadel kernel: usb 1-4: Manufacturer: LENOVO nov 02 12:09:39 citadel kernel: hub 1-4:1.0: USB hub found nov 02 12:09:39 citadel kernel: hub 1-4:1.0: 4 ports detected nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit nov 02 12:09:39 citadel kernel: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit ** Changed in: linux (Ubuntu) Status: Expired => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1777863 Title: [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1777863/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs