On Tue, Jul 30, 2013 at 07:33:46PM -0700, Julius Werner wrote: > > Wait a moment. Why does each of these attempts lead to a 5-second > > timeout? Why don't they fail immediately? > > Now that you mention it, that's a very good question. The kernel > enqueues a control transfer to the now disconnected address because > it's internal bookkeeping is not yet updated, but I guess that should > usually fail very fast from an xHC-internal transaction timeout. I > have now tried to debug the cause of this: I see the transfer being > enqueued and the doorbell triggered, but never get a transfer event > back from it (until the software timeout calls usb_kill_urb() which > stops the endpoint). With the same setup on a PantherPoint system I > get the same U1/U2 disable control messages on unplugging, but they > fail within <5ms with a transaction error... so I guess this must be a > LynxPoint hardware bug. > > Regardless, calling usb_reset_device() is still wrong and will at > least lead to pointless transfer attempts and error messages, so I > think my patch still has merit. Hmm, 5 seconds is the xHCI command timeout. Could the driver be possibly issuing either a Reset Device or Address Device command that simply times out? 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
