I just went back to using my Precision 5520 with the TB16 dock, after that duo was benched for a few months while I waited for a replacement battery to be shipped, and now the situation is similar but worse:

Every time I connect the dock cable, Linux tries to attached the USB hub, fails and disconnects the XHcI bus. Running the reset script details above (basically running "unbind" and the "bind" with the dock's bus address) allows the bus to be usable, though often it takes a couple of tries.

Attached is the dmesg log from connection through the error and the reset (timepoint documented in the log itself).

Interesting things that may or may not be related:
1. it takes a *very*long*time* for the system to connect the USB devices: the reset command occurred at 455, all the devices except the mouse got connected by 458 (13 seconds), with the mouse waiting until 471 (there were a few errors in the log specific to the logitech-hidpp-device, probably related).
2. I see a lot of `BAR 13: no space for [io  size 0xXXXX]` in dmesg, followed by `BAR 13: failed to assign [io  size 0xXXXX]`.

I'm running eoan full updated with kernel 5.3.0-24-generic. I have ran all the BIOS firmware updates and the MS-Windows "Dell Precision Optimizer" system updates including the Thunderbolt controller driver update.

Here's the fwupdmgr report:

```
Precision M5520 Thunderbolt Controller
  DeviceId:             51d36e5f8f25bea1d8707a72ab7b9386a98527ee
  Guid:                 c5364422-2ec3-5092-b30e-03bdb1a53e4a
  Summary:              Unmatched performance for high-speed I/O
  Plugin:               thunderbolt
  Flags:                internal|updatable|require-ac|registered
  Vendor:               Dell
  VendorId:             TBT:0x00D4
  Version:              26.01
  VersionFormat:        pair
  Icon:                 computer
  Created:              2019-12-09

Dell Thunderbolt Cable
  DeviceId:             aa4dfab63945b6e8ad913550d241978e3562f8bf
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 b4fd3cdf-4e3a-5090-a583-45367cfd6421
  Plugin:               thunderbolt
  Flags:                updatable|require-ac|registered
  Vendor:               Dell
  VendorId:             TBT:0x00D4
  Version:              16.00
  VersionFormat:        pair
  Icon:                 audio-card
  Created:              2019-12-09

Dell Thunderbolt Dock
  DeviceId:             64575ad9f31dbe3959942f4b2275c1c4d0ac2ac5
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 76cc74d4-f062-5b93-a11c-8d2a58a25848
  Plugin:               thunderbolt
  Flags:                updatable|require-ac|registered
  Vendor:               Dell
  VendorId:             TBT:0x00D4
  Version:              16.00
  VersionFormat:        pair
  Icon:                 audio-card
  Created:              2019-12-09

Precision 5520 System Firmware
  DeviceId:             f49999b6e3af5b4bf8ad1f2ed2922b76df457271
  Guid:                 34578c72-11dc-4378-bc7f-b643866f598c
  Plugin:               uefi
  Flags:                internal|updatable|require-ac|supported|registered|needs-reboot
  Checksum:             SHA1(de646f75ada7857150e2c6263dc59b1e51b944a8)
  Checksum:             SHA256(384c7594f033f64900148798be55939cdabfe502f8458febeb02884b920cf460)
  Version:              0.1.16.0
  VersionLowest:        0.1.16.0
  VersionFormat:        quad
  Icon:                 computer
  Created:              2019-12-09
  UpdateState:          success

Synaptics VMM3320 inside Dell WD15/TB16/TB18 wired Dock
  DeviceId:             7b3cbc344094ace839263dd4711c84ea99bb6dc3
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 152a9833-41e6-5c21-9dde-0ff8984f3e20
  Guid:                 0a52c8c7-26d5-59a0-ae44-6b00e276d775
  Guid:                 51000744-2de6-5a52-8a86-d5f69fd73d34
  Summary:              Multi-Stream Transport Device
  Plugin:               synapticsmst
  Flags:                updatable|registered
  Vendor:               Synaptics
  Version:              3.10.002
  VersionFormat:        triplet
  Icon:                 computer
  Created:              2019-12-09

Synaptics VMM3330 inside Dell WD15/TB16/TB18 wired Dock
  DeviceId:             d83854e8c81f5d47b0b99c8a3b42ae5127c75eb8
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 c0f73159-4fc0-509b-80f8-5f871f3751a8
  Guid:                 be025b25-ca5c-546c-97c6-ee2160ba489d
  Guid:                 190e8d7c-6bcf-5fab-94e7-4f8739eb90aa
  Summary:              Multi-Stream Transport Device
  Plugin:               synapticsmst
  Flags:                updatable|registered
  Vendor:               Synaptics
  Version:              3.10.002
  VersionFormat:        triplet
  Icon:                 computer
  Created:              2019-12-09

Dell TB16 Thunderbolt Cable
  DeviceId:             f8194a42320518472a2e67c1d89018c7a5219841
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 6dc832fc-5bb0-4e63-a2ff-02aaba5bc1dc
  Summary:              A Thunderbolt™ 3 docking station
  Plugin:               uefi
  Flags:                updatable|require-ac|registered|needs-reboot
  Vendor:               Dell Inc.
  Version:              0.0.3.18
  VersionFormat:        quad
  Icon:                 computer
  Created:              2019-12-09

Dell TB16 Port Controller 1
  DeviceId:             b3fa3dc04e3450450bb17910417562e5b6cf69d0
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 8fe183da-c94e-4804-b319-0f1ba5457a69
  Summary:              A Thunderbolt™ 3 docking station
  Plugin:               uefi
  Flags:                updatable|require-ac|registered|needs-reboot
  Vendor:               Dell Inc.
  Version:              0.1.2.17
  VersionFormat:        quad
  Icon:                 computer
  Created:              2019-12-09

Dell TB16 Port Controller 2
  DeviceId:             4bcf1477575b55912993240dd1edd8b0ebb6d491
  ParentDeviceId:       84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 1b52c630-86f6-4aee-9f0c-474dc6be49b6
  Summary:              A Thunderbolt™ 3 docking station
  Plugin:               uefi
  Flags:                updatable|require-ac|registered|needs-reboot
  Vendor:               Dell Inc.
  Version:              0.1.2.50
  VersionFormat:        quad
  Icon:                 computer
  Created:              2019-12-09

Dell TB16
  DeviceId:             84edf044a6b53037732cfc7591b65a8d36384cc9
  Guid:                 e7ca1f36-bf73-4574-afe6-a4ccacabf479
  Summary:              A Thunderbolt™ 3 docking station
  Plugin:               uefi
  Flags:                updatable|require-ac|registered|needs-reboot
  Vendor:               Dell Inc.
  Version:              0.0.0.0
  VersionFormat:        quad
  Icon:                 computer
  Created:              2019-12-09
```

I haven't had a spurious failure during work yet (just started working with it today), I'll report if that happens.