Hello,
I am running kernel 3.0.8 on x86_64 (a Zotac mini-ITX motherboard with a NEC USB 3.0 controller).
05:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03)
The problem is that USB 2.0 devices are not recognized at all when connected to USB 3.0 ports. But USB 3.0 devices work just fine. For instance, a Western Digital USB 3.0 hard disk appears in both lsusb (and lsusb -t) and achieves transfer rates of more than 100 MB/s.
Bus 002 Device 008: ID 1058:0730 Western Digital Technologies, Inc.
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M
|__ Port 2: Dev 2, If 0, Class=hub, Driver=hub/4p, 5000M
|__ Port 4: Dev 8, If 0, Class=stor., Driver=usb-storage, 5000M
(There is a Hama USB 3.0 hub connected to one of the USB 3.0 ports. Tried to connect my devices with/without the hub and also with/without a 5 meters long "active cable" for USB 3.0. The hard drive achieved the same transfer rates in all configurations.)
When it comes to USB 2.0 devices in USB 3.0 ports, they are silently ignored and nothing appears in dmesg. Two different flash drives, two different UVC cameras and a HP DVD writer -- all of them work normally on USB 2.0 ports, but don't seem to be recognized at all on USB 3.0.
(The motivation behind using USB 3.0 hubs for USB 2.0 devices is a multi-seat configuration with a USB 3.0 hub for each user, aiming to provide fast USB connectivity with just one cable.)
How can I diagnose these problems? Is this a known issue? A hint would help me a lot. :-)
Andrej
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