> 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. :-) Googling "linux usb debug" points out for example this: http://www.linux-usb.org/FAQ.html#ts7 So basically enable usb debug in kernel config, adjust the hub driver's DEBUG macro if needed, rebuild kernel, reboot, configure syslog to log KERN_DEBUG level ... watch the log, snap in usb2 device, see what happens. Debugfs might point out something as well. M -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
