my company purchased the USB 2.0 Loopback Plug (Firmware v2), and I ran some tests using the USB2Test (v1.1 (1000)) tool.
In some device configurations I observed lots of "device transceiver errors" I don't understand showing up:
* Loopback Plug is connected to root hub.
* External USB 2.0 Hub is connected to root hub.
* USB mouse is connected to external USB 2.0 hub.
This leads to a ~2:1 ratio "transceiver errors" : "operations" when running the "Loopback" test with 100% load.
Where do these errors come from? I use shielded USB 2.0 (full/high speed) cables; communication with the mouse (low-speed INT transfers) supposedly runs via USB 2.0 split transactions to the external hub, which I don't suspect of generating all these errors (should I?).
bigfoot (Horst Schirmeier)