On Thu, Jul 21, 2011 at 04:33:19PM -0400, Don Zickus wrote: > Hi Sarah, > > I am trying to debug a situation where when booting up my system with > 3.0.0-rc7, the xhci_hcd detects my usb3 WD disk and usb3 hub. However it > doesn't detect my usb3 Buffalo disk behind my hub. Does it detect other USB 3.0 devices behind the hub? What about USB 2.0 devices? > On my Panther point system's root hub > port 3 has the WD disk > port 4 has the VIA 4-port usb3 hub > > Using lsusb -t, I expected bit0 to represent the actual connect state of > the device under the hub port status. It shows a '0', meaning nothing is > connected (for the VIA hub). > > Hub Port Status: > Port 1: 0000.02a0 5Gbps power Rx.Detect > Port 2: 0000.02a0 5Gbps power Rx.Detect > Port 3: 0000.02a0 5Gbps power Rx.Detect > Port 4: 0000.02a0 5Gbps power Rx.Detect > > > Of course, if I unplug the disk and re-connect, it works as expected. > > I am trying to understand the situation in which the hub would not see a > device is connected (even when the power is enabled to the port it seems). SuperSpeed devices have to go through link training with the downstream port on their parent hub. So a device can be connected and powered, but fail to train at SuperSpeed. At that point, the device is supposed to fall back to High Speed. At the next device reset, the device attempts to link train to SuperSpeed again. It's entirely possible the device or the hub is failing to link train properly, and the device gets stuck in SuperSpeed mode somehow. Do you have a hub from a different vendor to try out? If not, I can dig up a TI prototype one and try it on my own Panther Point system. > I am not sure what logs to attach so I haven't attached any. dmesg would work. Sarah Sharp -- 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
