I'm using a USB hub in the Dell TB16 (240W) connected to a Dell Precision 5520 using Thunderbolt 3.

Every so often (can be several times in an hour if I'm really unlucky, some days it is less of a problem), the USB hub disconnects from the computer and the devices connected to it lose power and stop responding.

disconnecting and reconnecting the USB cables has no effect. I can restore functionality by instructing the xhci_hcd driver to unbind from the USB 3.0 Host Controller in the dock and to rebind to it using the commands:

echo -n "0000:0e:00.0" > /sys/bus/pci/drivers/xhci_hcd/unbind
echo -n "0000:0e:00.0" > /sys/bus/pci/drivers/xhci_hcd/bind

Here's the dmesg output when the USB hub disconnects:

279278.102701] xhci_hcd 0000:0e:00.0: ERROR unknown event type 15
[279283.021802] xhci_hcd 0000:0e:00.0: xHCI host not responding to stop endpoint command.
[279283.022145] xhci_hcd 0000:0e:00.0: xHCI host controller not responding, assume dead
[279283.022161] r8152 4-1.2:1.0 enxd481d731b2b1: Tx status -108
[279283.022199] xhci_hcd 0000:0e:00.0: HC died; cleaning up
[279283.022227] usb 3-1.5: Failed to suspend device, error -22
[279283.022234] usb 3-1: USB disconnect, device number 2
[279283.022235] usb 3-1.1: USB disconnect, device number 3
[279283.022236] usb 3-1.1.1: USB disconnect, device number 5
[279283.022237] usb 3-1.1.1.1: USB disconnect, device number 8
[279283.022238] usb 3-1.1.1.1.4: USB disconnect, device number 11
[279283.022326] usb 4-1: USB disconnect, device number 2
[279283.022328] usb 4-1.1: USB disconnect, device number 3
[279283.022329] usb 4-1.1.1: USB disconnect, device number 5
[279283.022998] usb 4-1.2: USB disconnect, device number 4
[279283.191217] usb 3-1.1.1.5: USB disconnect, device number 9
[279283.191730] usb 3-1.1.3: USB disconnect, device number 6
[279283.260810] usb 3-1.1.5: USB disconnect, device number 7
[279283.261350] usb 3-1.5: USB disconnect, device number 4

Here's dmesg output during the USB host controller reset:

279389.813889] xhci_hcd 0000:0e:00.0: remove, state 1                                                                                                                           
[279389.813894] usb usb4: USB disconnect, device number 1                                                                                                                        
[279389.814103] xhci_hcd 0000:0e:00.0: USB bus 4 deregistered                                                                                                                    
[279389.814107] xhci_hcd 0000:0e:00.0: remove, state 1                                                                                                                           
[279389.814110] usb usb3: USB disconnect, device number 1                                                                                                                        
[279389.881651] xhci_hcd 0000:0e:00.0: USB bus 3 deregistered                                                                                                                    
[279389.882133] xhci_hcd 0000:0e:00.0: xHCI Host Controller                                                                                                                      
[279389.882138] xhci_hcd 0000:0e:00.0: new USB bus registered, assigned bus number 3                                                                                             
[279389.949391] xhci_hcd 0000:0e:00.0: hcc params 0x0200e081 hci version 0x100 quirks 0x10000410                                                                                 
[279389.949979] usb usb3: New USB device found, idVendor=1d6b, idProduct=0002                                                                                                    
[279389.949981] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1                                                                                               
[279389.949982] usb usb3: Product: xHCI Host Controller                                                                                                                          
[279389.949983] usb usb3: Manufacturer: Linux 4.15.0-15-generic xhci-hcd                                                                                                         
[279389.949983] usb usb3: SerialNumber: 0000:0e:00.0                                                                                                                             
[279389.950117] hub 3-0:1.0: USB hub found                                                                                                                                       
[279389.950135] hub 3-0:1.0: 2 ports detected                                                                                                                                    
[279389.950310] xhci_hcd 0000:0e:00.0: xHCI Host Controller                                                                                                                      
[279389.950314] xhci_hcd 0000:0e:00.0: new USB bus registered, assigned bus number 4                                                                                             
[279389.951098] usb usb4: We don't know the algorithms for LPM for this host, disabling LPM.                                                                                     
[279389.951117] usb usb4: New USB device found, idVendor=1d6b, idProduct=0003                                                                                                    
[279389.951119] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1                                                                                               
[279389.951120] usb usb4: Product: xHCI Host Controller                                                                                                                          
[279389.951121] usb usb4: Manufacturer: Linux 4.15.0-15-generic xhci-hcd                                                                                                         
[279389.951122] usb usb4: SerialNumber: 0000:0e:00.0                                                                                                                             
[279389.951306] hub 4-0:1.0: USB hub found
[279389.951321] hub 4-0:1.0: 2 ports detected
[279390.299396] usb 4-1: new SuperSpeed USB device number 2 using xhci_hcd
[279390.321750] usb 4-1: New USB device found, idVendor=0424, idProduct=5807
[279390.321752] usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279390.321753] usb 4-1: Product: USB5807 Hub
[279390.321754] usb 4-1: Manufacturer: Microchip
[279390.341684] hub 4-1:1.0: USB hub found
[279390.342312] hub 4-1:1.0: 7 ports detected
[279390.513286] usb 3-1: new high-speed USB device number 2 using xhci_hcd
[279390.750013] usb 3-1: New USB device found, idVendor=0424, idProduct=2807
[279390.750015] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279390.750016] usb 3-1: Product: USB2807 Hub
[279390.750017] usb 3-1: Manufacturer: Microchip
[279390.769651] hub 3-1:1.0: USB hub found
[279390.769793] hub 3-1:1.0: 7 ports detected
[279390.839440] usb 4-1.1: new SuperSpeed USB device number 3 using xhci_hcd
[279390.861567] usb 4-1.1: New USB device found, idVendor=0424, idProduct=5734
[279390.861568] usb 4-1.1: New USB device strings: Mfr=2, Product=3, SerialNumber=0
[279390.861569] usb 4-1.1: Product: USB5734
[279390.861570] usb 4-1.1: Manufacturer: Microchip Tech
[279390.881472] hub 4-1.1:1.0: USB hub found
[279390.882171] hub 4-1.1:1.0: 5 ports detected
[279390.991442] usb 4-1.2: new SuperSpeed USB device number 4 using xhci_hcd
[279391.015809] usb 4-1.2: New USB device found, idVendor=0bda, idProduct=8153
[279391.015811] usb 4-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=6
[279391.015812] usb 4-1.2: Product: USB 10/100/1000 LAN
[279391.015813] usb 4-1.2: Manufacturer: Realtek
[279391.015814] usb 4-1.2: SerialNumber: 000001000000
[279391.089207] usb 3-1.1: new high-speed USB device number 3 using xhci_hcd
[279391.211462] usb 3-1.1: New USB device found, idVendor=0424, idProduct=2734
[279391.211481] usb 3-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279391.211482] usb 3-1.1: Product: USB2734
[279391.211483] usb 3-1.1: Manufacturer: Microchip Tech
[279391.231366] hub 3-1.1:1.0: USB hub found
[279391.231502] hub 3-1.1:1.0: 5 ports detected
[279391.302796] usb 4-1.2: reset SuperSpeed USB device number 4 using xhci_hcd
[279391.355371] usb 4-1.2: Dell TB16 Dock, disable RX aggregation
[279391.370639] r8152 4-1.2:1.0 (unnamed net_device) (uninitialized): Using pass-thru MAC addr d4:81:d7:31:b2:b1
[279391.401126] usb 3-1.5: new high-speed USB device number 4 using xhci_hcd
[279391.425377] r8152 4-1.2:1.0 eth0: v1.09.9
[279391.588750] usb 3-1.5: New USB device found, idVendor=0bda, idProduct=4014
[279391.588752] usb 3-1.5: New USB device strings: Mfr=3, Product=1, SerialNumber=2
[279391.588754] usb 3-1.5: Product: USB Audio
[279391.588755] usb 3-1.5: Manufacturer: Generic
[279391.588757] usb 3-1.5: SerialNumber: 200901010001
[279391.663127] usb 4-1.1.1: new SuperSpeed USB device number 5 using xhci_hcd
[279391.685637] usb 4-1.1.1: New USB device found, idVendor=0424, idProduct=5734
[279391.685639] usb 4-1.1.1: New USB device strings: Mfr=2, Product=3, SerialNumber=0
[279391.685640] usb 4-1.1.1: Product: USB5734
[279391.685641] usb 4-1.1.1: Manufacturer: Microchip Tech
[279391.812609] hub 4-1.1.1:1.0: USB hub found
[279391.813185] hub 4-1.1.1:1.0: 5 ports detected
[279391.973147] usb 3-1.1.1: new high-speed USB device number 5 using xhci_hcd
[279392.095383] usb 3-1.1.1: New USB device found, idVendor=0424, idProduct=2734
[279392.095386] usb 3-1.1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279392.095388] usb 3-1.1.1: Product: USB2734
[279392.095389] usb 3-1.1.1: Manufacturer: Microchip Tech
[279392.104109] r8152 4-1.2:1.0 enxd481d731b2b1: renamed from eth0
[279392.165057] IPv6: ADDRCONF(NETDEV_UP): enxd481d731b2b1: link is not ready
[279392.187087] IPv6: ADDRCONF(NETDEV_UP): enxd481d731b2b1: link is not ready
[279392.398705] hub 3-1.1.1:1.0: USB hub found
[279392.398894] hub 3-1.1.1:1.0: 5 ports detected
[279392.625122] usb 3-1.1.3: new full-speed USB device number 6 using xhci_hcd
[279392.884608] usb 3-1.1.3: New USB device found, idVendor=046d, idProduct=c52b
[279392.884609] usb 3-1.1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279392.884610] usb 3-1.1.3: Product: USB Receiver
[279392.884611] usb 3-1.1.3: Manufacturer: Logitech
[279392.934819] logitech-djreceiver 0003:046D:C52B.0091: hiddev1,hidraw3: USB HID v1.11 Device [Logitech USB Receiver] on usb-0000:0e:00.0-1.1.3/input2
[279393.062222] logitech-hidpp-device 0003:046D:402D.0092: hidraw4: USB HID v1.11 Keyboard [Logitech M560] on usb-0000:0e:00.0-1.1.3:1
[279393.133173] usb 3-1.1.5: new high-speed USB device number 7 using xhci_hcd
[279393.260962] usb 3-1.1.5: New USB device found, idVendor=0424, idProduct=274c
[279393.260965] usb 3-1.1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[279393.260966] usb 3-1.1.5: Product: Hub Controller
[279393.260967] usb 3-1.1.5: Manufacturer: Microchip Tech
[279393.337238] usb 3-1.1.1.1: new high-speed USB device number 8 using xhci_hcd
[279393.463217] usb 3-1.1.1.1: New USB device found, idVendor=05e3, idProduct=0608
[279393.463236] usb 3-1.1.1.1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[279393.463237] usb 3-1.1.1.1: Product: USB2.0 Hub
[279393.839721] hid-generic 0003:0424:274C.0093: hiddev2,hidraw5: USB HID v1.10 Device [Microchip Tech Hub Controller] on usb-0000:0e:00.0-1.1.5/input0
[279393.857686] hub 3-1.1.1.1:1.0: USB hub found
[279393.858162] hub 3-1.1.1.1:1.0: 4 ports detected
[279393.985185] usb 3-1.1.1.5: new high-speed USB device number 9 using xhci_hcd

Software:

Ubuntu bionic beta
Uname: Linux xxxxx 4.15.0-15-generic #16-Ubuntu SMP Wed Apr 4 13:58:14 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

lspci:

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 05)
00:01.0 PCI bridge: Intel Corporation Skylake PCIe Controller (x16) (rev 05)
00:02.0 VGA compatible controller: Intel Corporation Device 591b (rev 04)
00:04.0 Signal processing controller: Intel Corporation Skylake Processor Thermal Subsystem (rev 05)
00:14.0 USB controller: Intel Corporation Sunrise Point-H USB 3.0 xHCI Controller (rev 31)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-H Thermal subsystem (rev 31)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-H Serial IO I2C Controller #0 (rev 31)
00:15.1 Signal processing controller: Intel Corporation Sunrise Point-H Serial IO I2C Controller #1 (rev 31)
00:16.0 Communication controller: Intel Corporation Sunrise Point-H CSME HECI #1 (rev 31)
00:17.0 SATA controller: Intel Corporation Sunrise Point-H SATA controller [AHCI mode] (rev 31)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #1 (rev f1)
00:1c.1 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #2 (rev f1)
00:1d.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #9 (rev f1)
00:1d.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #13 (rev f1)
00:1d.6 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #15 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-H LPC Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-H PMC (rev 31)
00:1f.3 Audio device: Intel Corporation CM238 HD Audio Controller (rev 31)
00:1f.4 SMBus: Intel Corporation Sunrise Point-H SMBus (rev 31)
01:00.0 3D controller: NVIDIA Corporation GM107GLM [Quadro M1200 Mobile] (rev ff)
02:00.0 Network controller: Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter (rev 32)
03:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader (rev 01)
04:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM961/PM961
06:00.0 PCI bridge: Intel Corporation DSL6340 Thunderbolt 3 Bridge [Alpine Ridge 2C 2015]
07:00.0 PCI bridge: Intel Corporation DSL6340 Thunderbolt 3 Bridge [Alpine Ridge 2C 2015]
07:01.0 PCI bridge: Intel Corporation DSL6340 Thunderbolt 3 Bridge [Alpine Ridge 2C 2015]
07:02.0 PCI bridge: Intel Corporation DSL6340 Thunderbolt 3 Bridge [Alpine Ridge 2C 2015]
08:00.0 System peripheral: Intel Corporation DSL6340 Thunderbolt 3 NHI [Alpine Ridge 2C 2015]
09:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0a:01.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0a:04.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0c:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0d:01.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0d:04.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
0e:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller