1 Thunderbolt controller for 2 PCIe Root Port

[RichardP]

Hello.

I would like to ask, how Thunderbolt controller works?
My laptop has 2x Thunderbolt 4, but it only has 1 Thunderbolt controller.
Checked with HWiNFO->Bus->PCI bus, there are 2 "Integrated Thunderbolt" which known as "PCI Express Root Port" on device manager. And each of those port has its own PCI Express x4 Bus. I also checked on Device Manager->View by connection, there are 2x PCI Express Root Port, and currently they are detected as "Integrated Thunderbolt" on HWiNFO64 and no devices are connected to that root port.
Interestingly enough, i can adjust the "Resource Allocation" for each Thunderbolt ports despite having only 1 Thunderbolt controller.

So, i would like to know is it means 1 Thunderbolt 4 controller can handles 2 Thunderbolt ports at the same time, and allocate PCIe Lanes for each ports independently? Because what i know is that, all of
Thunderbolt 4 controllers supports dual ports and up-to quad ports. I planned to use eGPU and Thunderbolt docks in the future, so this information will greatly help me!

For more information, I'll attach some images I've taken from Device manager and HWiNFO.

[AlphaTop89]

...that setup is indeed possible and aligns with the capabilities of Thunderbolt 4 controllers... Thunderbolt 4 controllers can handle multiple ports simultaneously. Each port can independently allocate PCIe lanes, allowing for efficient resource management 

how this works, A Thunderbolt 4 controller can support up to four ports. In your case, the controller manages two ports, each with its own PCIe x4 bus. You can adjust resource allocation for each port independently, which is useful for optimizing performance based on connected devices. Thunderbolt 4 uses PCIe tunneling to manage data transfer. This means the controller can dynamically allocate PCIe lanes to each port as needed.

Given your plans to use eGPUs and Thunderbolt docks, this setup should work well. The controller will manage the data flow and resource allocation efficiently, ensuring optimal performance for your peripherals.

[RichardP]

you're right, Thunderbolt 4 controllers supports up-to Quad ports. But, lack of information and Intel never confirms (at least not yet) whether these controllers can allocate each ports its own x4 PCIe Lanes independently or not.
I've searched online, and none of them have the answer, but Google's built-in AI Summary from searching saying that It's not possible for Thunderbolt 4 controllers to allocate x4 PCIe Lanes to each ports independently.

So I'm here to confirm whether it's true that 1 Controller can't allocate x4 PCIe Lanes to each ports independently, or is there any limitations of how much ports that Thunderbolt 4 controllers can allocate the x4 PCIe Lanes independently until it'll use the sharing bandwidth from one of the ports because it has reached its own limits?

This is interesting because previously, Thunderbolt 3 controllers can only manage 1 port at the same time, and if manufacturer wants to add the second Thunderbolt 3 port, then they'll need to add the second Thunderbolt 3 controller.
So, since Thunderbolt 4 controllers supports dual and up-to quad ports, is it possible that these ports (At least 2 Thunderbolt ports) can have their own PCIe Lanes independently from one controller?

[RichardP]

So, no one has the answer for this questions, not even Intel staff members?