Hi, there is an issue with the Thunderbolt driver for the Ice Lake CPU i7-1065G7 (used for example in the Dell XPS 7390 2-in-1) and Thunderbolt docks (Dell WD19TB). Randomly after anywhere between a few minutes and a few hours of use, the Thunderbolt dock will have a "disconnect event" in which all peripherals disconnect briefly and all external monitors flicker and lose signal. USB Mass Storage connected to the dock suffer IO errors, and the monitors briefly regain signal only to then lose it for good. The dock must be reconnected or the system rebooted to fix it for a time. dmesg may or may not show the following line when it happens: [ 4552.598580] i915 0000:00:02.0: [drm] *ERROR* CPU pipe B FIFO underrun The issue was reported by multiple users to intel-drm here: https://gitlab.freedesktop.org/drm/intel/-/issues/1453 But it seems to be related to Thunderbolt, not the i915 driver, as non-Thunderbolt external screens work fine, and the failure sometimes affects everything attached to the Thunderbolt dock, not just the monitors (dmesg then shows USB reconnects and "xHCI host controller not responding, assume dead"). So I'm sending this to the PCI mailing list to which all Thunderbolt issues are being redirected. The laptop and dock work flawlessly under Windows (ruling out hardware/memory faults), and the issue persists ever since the 5.4 kernel all the way up to the most recent 5.7.4. If you need any more information let me know. Regards
