20.04 – External monitor doesn’t come back / system unstable after screen blank/lock

Dell XPS 13 9370 laptop

Kensington SD4600P USB-C Dock With Power Delivery (plugged in through one of the two left side “thunderbolt” usb-c ports)

Samsung ultrawide curved monitor (connected to dock via displayport cable)

Ubuntu 20.04.2 LTS

I’ve updated all firmware/drivers/BIOS and can’t figure out why this happens. Whenever I let the screen go blank and try to wake it back up, my external monitor stays off and my system becomes almost completely unreponsive until I unplug the dock completely. I have to then restart the laptop while the dock is plugged in to get the monitor to come back (plugging the dock in at any point after the system is already powered on doesn’t work).

Full dmesg output: https://pastebin.com/YPV5Bqf1

I unplugged two devices (device number 6 and device number 8), on line 1245 in the above paste, before the 1-minute screen timer started for reference, and the ouput freezes until I unplug all devices from the system (3 minutes later at the 18:44 timestamp) so I’m not sure if the output that follows that sequence is related to the problem:

( +35.452467) usb 1-1.2: USB disconnect, device number 6
(  +2.559742) usb 1-1.3: USB disconnect, device number 8
(Jun 7 18:44) usb 1-1: USB disconnect, device number 2
(  +0.000006) usb 1-1.1: USB disconnect, device number 4
(  +0.152515) usb 2-1: USB disconnect, device number 2
(  +0.089232) usb 1-1.4: USB disconnect, device number 9
(  +2.599329) usb 3-2: USB disconnect, device number 2
(  +0.000008) usb 3-2.1: USB disconnect, device number 4
(  +0.000004) usb 3-2.1.1: USB disconnect, device number 6
(  +0.000248) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579: unregister 'ax88179_178a' usb-0000:39:00.0-2.1.1, Cypress GX3 SuperSpeed to Gigabit Ethernet Controller
(  +0.000109) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579: Failed to read reg index 0x0002: -19
(  +0.000007) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579: Failed to write reg index 0x0002: -19
(  +0.027897) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579 (unregistered): Failed to write reg index 0x0002: -19
(  +0.000017) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579 (unregistered): Failed to write reg index 0x0001: -19
(  +0.000013) ax88179_178a 3-2.1.1:1.0 enxe8ea6a158579 (unregistered): Failed to write reg index 0x0002: -19
(  +0.154970) xhci_hcd 0000:39:00.0: xHCI host controller not responding, assume dead
(  +0.000011) xhci_hcd 0000:39:00.0: HC died; cleaning up
(  +0.000725) xhci_hcd 0000:39:00.0: Timeout while waiting for configure endpoint command
(  +0.000127) usb 3-2.1.2: USB disconnect, device number 5
(  +0.000712) usb 3-2.3: USB disconnect, device number 3
(  +0.018592) xhci_hcd 0000:39:00.0: remove, state 4
(  +0.000003) usb usb4: USB disconnect, device number 1
(  +0.000170) xhci_hcd 0000:39:00.0: USB bus 4 deregistered
(  +0.000005) xhci_hcd 0000:39:00.0: remove, state 1
(  +0.000001) usb usb3: USB disconnect, device number 1
(  +0.000117) xhci_hcd 0000:39:00.0: Host halt failed, -19
(  +0.000001) xhci_hcd 0000:39:00.0: Host not accessible, reset failed.
(  +0.000062) xhci_hcd 0000:39:00.0: USB bus 3 deregistered
(  +0.019947) pci_bus 0000:04: Allocating resources
(  +0.000029) pcieport 0000:04:02.0: bridge window (mem 0x00100000-0x000fffff 64bit pref) to (bus 39) add_size 200000 add_align 100000
(  +0.000005) pcieport 0000:04:02.0: BAR 15: no space for (mem size 0x00200000 64bit pref)
(  +0.000000) pcieport 0000:04:02.0: BAR 15: failed to assign (mem size 0x00200000 64bit pref)
(  +0.000002) pcieport 0000:04:02.0: BAR 15: no space for (mem size 0x00200000 64bit pref)
(  +0.000001) pcieport 0000:04:02.0: BAR 15: failed to assign (mem size 0x00200000 64bit pref)
(  +4.977393) pcieport 0000:04:00.0: Refused to change power state, currently in D3
(  +0.002161) pci_bus 0000:05: busn_res: (bus 05) is released
(  +0.000350) pci_bus 0000:06: busn_res: (bus 06-38) is released
(  +0.000068) pci_bus 0000:39: busn_res: (bus 39) is released
(  +0.000135) pci_bus 0000:3a: busn_res: (bus 3a-6d) is released
(  +0.000902) pci_bus 0000:04: busn_res: (bus 04-6d) is released