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I have a HP laptop with Dell WD19TBS thunderbolt dock (I tried Lenovo thunderbolt dock as well with the same problem) and when I connect USB-C cable from dock to my laptop after suspend, both external displays connected to dock are not recognized. I'm on Ubuntu 22 with xwayland.

I have latest HP bios and latest dock firmware. fwupdmgr get-updates says 'No available updates' I checked dmesg and the only error there is this one i915 0000:00:02.0: [drm] *ERROR* link address NAK received which apparently is connected to the issue, but I can't seem to find a solution.

One interesting thing is that when I disconnect and reconnect the dock (even if displays are not recognized before this disconnect) in just about the right time - not too fast, not too slow - circa 1 second - displays sometimes start to work and there is no error in dmesg. System restart helps always. Any suggestions appreciated.

Giacomo1968
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MartinM
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1 Answers1

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I have a Dell Latitude 7370 laptop and a HP Thunderbolt 230W G2 dock, connected to an external 4K monitor. The distribution used is Alpine Linux with 6.6.16-lts kernel and Sway window manager (Xwayland disabled). In the BIOS settings, I have set Thunderbolt security to No Security. This is mentioned in the Arch Linux wiki for preventing authorization issues.

I encountered the exact same error. I tried upgrading the firmware of both the laptop and the dock, under Windows, to no avail. The newer "edge" kernel also made no difference.

I have so far discovered two solutions. One is the method you mentioned: try repeatedly reconnect the Thunderbolt cable. Sometimes it will work.

The other is to suspend the laptop, then wake it up, dmesg then outputs:

[  329.250419] drm card1-DP-3: PM: parent card1 should not be sleeping
[  329.250764] drm card1-DP-4: PM: parent card1 should not be sleeping
[  329.250946] drm card1-DP-5: PM: parent card1 should not be sleeping
[  329.251235] i915 0000:00:02.0: [drm] [ENCODER:94:DDI A/PHY A] is disabled/in DSI mode with an ungated DDI clock, gate it
[  329.251249] i915 0000:00:02.0: [drm] [ENCODER:102:DDI B/PHY B] is disabled/in DSI mode with an ungated DDI clock, gate it
[  329.251262] i915 0000:00:02.0: [drm] [ENCODER:117:DDI C/PHY C] is disabled/in DSI mode with an ungated DDI clock, gate it

The last non-solution I discovered is to use ChromeOS Flex. Somehow Google managed to smooth out the rough corners in their Linux distribution: plugging in the cable always result in a working external display.