PCI Bus reset on display power event when Thunderbolt plugged in
(repost of https://bugzilla.kernel.org/show_bug.cgi?id=211337 as IDK if it's a IOMMU or DRM issue)
The device, a Dell XPS 9300, works fine with external displays attached to the usb-c docking stations.
The Caldigit TS3 Plus docking station also works fine on its own as long as no external display is attached.
Now if I connect an external display while the Caldigit TS3 Plus docking station is connected, either via the docking station itself or another adapter, every time a "power event" happens on the external monitor (such as connecting, disconnecting, rearranging the displays on Gnome), the entire PCI bus seems to disappear with these messages in the logs:
Jan 24 22:20:07 XPS-20 kernel: pcieport 0000:00:07.0: pciehp: Slot(0): Link Down
Jan 24 22:20:07 XPS-20 kernel: pcieport 0000:00:07.0: pciehp: Slot(0): Card not present
Jan 24 22:20:07 XPS-20 kernel: pcieport 0000:02:04.0: can't change power state from D3cold to D0 (config space inaccessible)
Jan 24 22:20:07 XPS-20 kernel: igb 0000:06:00.0: removed PHC on eth0
Jan 24 22:20:07 XPS-20 kernel: igb 0000:06:00.0 eth0: PCIe link lost
Jan 24 22:20:07 XPS-20 kernel: i2c_hid i2c-WCOM4941:00: supply vdd not found, using dummy regulator
Jan 24 22:20:07 XPS-20 kernel: i2c_hid i2c-WCOM4941:00: supply vddl not found, using dummy regulator
System and docking station firmwares are up to date, tried without iommu (but I guess TB forces it on anyways, or it is handled by UEFI). Works fine on Windows 10. Also, interestingly, external displays just plain don't work at all if I connect a TB device and disable secure boot.
I will also mention that my device has 32GB or RAM as I find some similarities in the logs with this bug report.