Multiple USB cameras limited to 10Gb/s total

On the AGX Orin DevKit I am trying to understand why 4 USB cameras seem to be channeled through the same 10Gb/s SuperSpeedPlus root hub when attached to 2 USB-C and 2 USB-A (Gen2) ports. Please see this post in another forum: 4 USB cameras using same USB Bus - #6 by stetson

All of the devices share 10Gb/s that connect to the same bus.


Shane - how can I take advantage of the 2 SuperSpeedPlus hubs through USB. I thought that ports 0 and 1 used one of the SuperSpeedPlus hubs and ports 2 and 3 used the second SuperSpeedPlus hub. Is the bottleneck at the Bus level? Are the SuperSpeedPlus root hubs before or after the Bus? Do the physical ports transfer data to the Bus first or to the USB Root Hubs first?

The detail of USB lane mapping on AGX Orin developer kit is stated in
4 USB cameras using same USB Bus - #3 by DaneLLL

If you have made use of the type-A and type-C port on the developer kit but still cannot achieve target performance, it may be due to concurrent access of the multiple devices. Please consider the suggestion from other users to use PCIe switch for utilizing PCIe bandwidth.

And if the USB devices requires significant power, we would suggest supply the device with external power supply. Power from the embedded hub is 2A in total, for all connected devices.

Dane - there is a bottleneck in the USB interface somewhere. According to the info about the USB lane mapping provided earlier (copied below), a setup with 2 cameras on 1 SuperSpeedPlus hub and and 2 cameras on the other SuperSpeedPlus hub should be able to transfer 3.2 Gb/s from each camera without any problem. For some reason the concurrent transfer of 6.4 Gb/s of data on both SuperSpeedPlus hubs hits a bottleneck and only works if I manually reduce the data throughput to less than 10 Gb/s for all 4 cameras combined. Each Hub may be able handle 10Gb/s, but the two Hubs cannot handle 10GB/s at the same time. It’s almost as if there is a 10GB/s limitation after the two Hubs. Could this be the case?

[quote=“DaneLLL, post:3, topic:288786”]
USB 3.2 port 0 and port 1 are connected to the same SuperSpeedPlus hub to share 10 Gbps total bandwidth, while USB 3.2 port 2 and port 3 share another 10 Gbps total bandwidth