TRX40 AMD USB controllers question

[fabiosun]

I'd like to find the right words to express my question
I would like to understand the relationship if there is between the various USB controllers that I can find with the command from shell: lspci -nnk

Spoiler: USB controllers

04:00.3 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Starship USB 3.0 Host Controller [1022:148c]
Subsystem: Micro-Star International Co., Ltd. [MSI] Starship USB 3.0 Host Controller [1462:7c60]
23:00.3 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Starship USB 3.0 Host Controller [1022:148c]
Subsystem: Micro-Star International Co., Ltd. [MSI] Starship USB 3.0 Host Controller [1462:7c60]
Kernel driver in use: vfio-pci
Kernel modules: xhci_pci
23:00.4 Audio device [0403]: Advanced Micro Devices, Inc. [AMD] Starship/Matisse HD Audio Controller [1022:1487]
Subsystem: Micro-Star International Co., Ltd. [MSI] Starship/Matisse HD Audio Controller [1462:cb60]
Kernel driver in use: vfio-pci
46:00.1 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller [1022:149c]
Subsystem: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller [1022:1486]
Kernel driver in use: vfio-pci
Kernel modules: xhci_pci
46:00.3 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller [1022:149c]
Subsystem: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller [1022:148c]
Kernel driver in use: vfio-pci
Kernel modules: xhci_pci

and this Qemu configuration file:

Spoiler: /usr/share/qemu-server/pve-q35-4.0.cfg

[device "ehci"]
driver = "ich9-usb-ehci1"
multifunction = "on"
bus = "pcie.0"
addr = "1d.7"

[device "uhci-1"]
driver = "ich9-usb-uhci1"
multifunction = "on"
bus = "pcie.0"
addr = "1d.0"
masterbus = "ehci.0"
firstport = "0"

[device "uhci-2"]
driver = "ich9-usb-uhci2"
multifunction = "on"
bus = "pcie.0"
addr = "1d.1"
masterbus = "ehci.0"
firstport = "2"

[device "uhci-3"]
driver = "ich9-usb-uhci3"
multifunction = "on"
bus = "pcie.0"
addr = "1d.2"
masterbus = "ehci.0"
firstport = "4"

[device "ehci-2"]
driver = "ich9-usb-ehci2"
multifunction = "on"
bus = "pcie.0"
addr = "1a.7"

[device "uhci-4"]
driver = "ich9-usb-uhci4"
multifunction = "on"
bus = "pcie.0"
addr = "1a.0"
masterbus = "ehci-2.0"
firstport = "0"

[device "uhci-5"]
driver = "ich9-usb-uhci5"
multifunction = "on"
bus = "pcie.0"
addr = "1a.1"
masterbus = "ehci-2.0"
firstport = "2"
[device "uhci-6"]
driver = "ich9-usb-uhci6"
multifunction = "on"
bus = "pcie.0"
addr = "1a.2"
masterbus = "ehci-2.0"
firstport = "4"

# FIXME: Remove this audio0 device at the next possible time
# see: https://pve.proxmox.com/pipermail/pve-devel/2019-July/038417.html
# https://pve.proxmox.com/pipermail/pve-devel/2019-July/038428.html
[device "audio0"]
driver = "ich9-intel-hda"
bus = "pcie.0"
addr = "1b.0"


[device "ich9-pcie-port-1"]
driver = "pcie-root-port"
x-speed = "16"
x-width = "32"
multifunction = "on"
bus = "pcie.0"
addr = "1c.0"
port = "1"
chassis = "1"

[device "ich9-pcie-port-2"]
driver = "pcie-root-port"
x-speed = "16"
x-width = "32"
multifunction = "on"
bus = "pcie.0"
addr = "1c.1"
port = "2"
chassis = "2"

[device "ich9-pcie-port-3"]
driver = "pcie-root-port"
x-speed = "16"
x-width = "32"
multifunction = "on"
bus = "pcie.0"
addr = "1c.2"
port = "3"
chassis = "3"

[device "ich9-pcie-port-4"]
driver = "pcie-root-port"
x-speed = "16"
x-width = "32"
multifunction = "on"
bus = "pcie.0"
addr = "1c.3"
port = "4"
chassis = "4"

##
# Example PCIe switch with two downstream ports
#
#[device "pcie-switch-upstream-port-1"]
# driver = "x3130-upstream"
# bus = "ich9-pcie-port-4"
# addr = "00.0"
#
#[device "pcie-switch-downstream-port-1-1"]
# driver = "xio3130-downstream"
# multifunction = "on"
# bus = "pcie-switch-upstream-port-1"
# addr = "00.0"
# port = "1"
# chassis = "5"
#
#[device "pcie-switch-downstream-port-1-2"]
# driver = "xio3130-downstream"
# multifunction = "on"
# bus = "pcie-switch-upstream-port-1"
# addr = "00.1"
# port = "1"
# chassis = "6"



[device "pcidmi"]
driver = "i82801b11-bridge"
bus = "pcie.0"
addr = "1e.0"

[device "pci.0"]
driver = "pci-bridge"
bus = "pcidmi"
addr = "1.0"
chassis_nr = "1"

[device "pci.1"]
driver = "pci-bridge"
bus = "pcidmi"
addr = "2.0"
chassis_nr = "2"

[device "pci.2"]
driver = "pci-bridge"
bus = "pcidmi"
addr = "3.0"
chassis_nr = "3"

[device "pci.3"]
driver = "pci-bridge"
bus = "pcidmi"
addr = "4.0"
chassis_nr = "4"

in practice, it seems to me that the USB controller that manages all the USBs present on the motherboard is the:
46:00 23:00.3 04:00.3
divided into 46: 00.1 and 46: 00.3, 23:00.3,04:00.3

the other USB controllers visible in the previous spoiler don't seem to bring new USB to my system.

Another aspect that I would like to understand is this:
Because by completely switching (passthrough)the two USB controllers 46: 00.1 and 46: 00.3 it is no longer possible to individually switch(pass) the USB devices connected through the Web interface and the corresponding Hardware / add / USB Device option.
Only by passing the controllers above in this space I no longer see any USB device (they are not seen in the drop down menu, while they are there if I do not pass the controller)
Are the virtual usb devices inside pve-q35-4.0.cfg set to have compatibility with older systems?
Is there a wiki to be able to understand and customize those voices (always if it does not damage the excellent functionality of Proxmox)

Thanks in advance for your clarifications