Looking for support or debugging suggestions to figure out why my HP
Spectre x360 (Icelake) laptop doesn't successfully hotplug with an HP
Thunderbolt 3 dock. I'm using 5.8.0-rc7-next-20200729. The dock's
firmwares have been updated from a system running Windows. The HP laptop
is using the latest BIOS as of last week, and nvm_version is "80.0":

% cat /sys/devices/pci0000:00/0000:00:0d.2/domain0/0-0/nvm_version 
80.0

Cold booting the system with the dock attached provides working
ethernet, USB hub, etc. Unplugging and replugging the dock does not
work, leaving it only providing power.

Attached are dmesg, lspci -vvnnt output, and /proc/iomem captured (1) at
coldboot with the dock attached, (2) after unplugging the dock, and (3)
after hotplugging the dock; and my kernel .config.

For search engines, the most apparent failure in dmesg is:

xhci_hcd 0000:2e:00.0: enabling device (0000 -> 0002)
xhci_hcd 0000:2e:00.0: xHCI Host Controller
xhci_hcd 0000:2e:00.0: new USB bus registered, assigned bus number 5
xhci_hcd 0000:2e:00.0: Host halt failed, -19
xhci_hcd 0000:2e:00.0: can't setup: -19
xhci_hcd 0000:2e:00.0: USB bus 5 deregistered
xhci_hcd 0000:2e:00.0: init 0000:2e:00.0 fail, -19
tg3 0000:2f:00.0: enabling device (0000 -> 0002)
tg3 0000:2f:00.0: phy probe failed, err -19
tg3 0000:2f:00.0: Problem fetching invariants of chip, aborting

Help? Thanks!
Matt