On Wed, 7 Jul 2010, Paul Mortier wrote: > Hi, > apologies if this is wrong place to ask, but I've got a problem with > a USB dongle appearing then disappearing in /dev/bus/usb. The dongle is > an authentication dongle for some software that runs on WindowsXP, which > I would like to have running in a virtual machine, but the file need to > be present so that it can be passed through to the virtual machine. > > The problem first showed itself in that there is an LED on the dongle > which in Windows flickers briefly when the dongle is inserted, then > stays lit except for the occasional flicker whilst the software is > running. When inserted in Linux it instead continuously flickers. I've > captured the USB activity in a WireShark log, dmesg log and a separate > usbmon text output. Looking at that it seems that the dongle almost > connects correctly, but that after having read the strings at locations > 0, 2, 1 and 3, then setting the configuration. It then tries to read a > string from location 4 which gets some valid data back. Finally the > host tries to read from location 5 and gets an error. Sometime during > that the host creates the /dev/bus/usb file, but shortly (0.1s or so) > after that there's a disconnect, followed by the dongle reconnecting and > starting the loop over again. I'm guessing that the dongle isn't > handling the read request correctly and resetting itself. > > With a bit of luck I captured the lsusb output for the split second the > file existed, which shows the information that has been read before the > disconnect happens. The dongle has vendor:product 04b4:0526 > > I've tried this under kernel 2.6.35-rc4 and the current debian testing > kernel 2.6.32 package, both for x86-64 (processor is Intel core2 duo), > and also 2.6.22-3-486 on an old p200 with the same result. > > I'm aware that this is a problem most likely caused by the dongle not > following standards, given that I haven't had any other USB problems, > but I was wondering if anyone could help point toward a possible > solution that stops the extra string reads for this device that I think > are causing the problem? If the disconnect could be avoided then it > might be possible to pass the file through the virtual machine for the > Windows-only dongle drivers to handle. I hope I've provided enough > useful information, please let me know if there's anything else I could > provide, According to the usbmon log, your diagnosis is correct. The device fails when asked for its interface string descriptor. You can prevent the kernel from getting the configuration and interface string descriptors by adding an entry to the drivers/usb/core/quirks.c file. It should look like the Saitek Cyborg Gold Joystick entry, with the USB_QUIRK_CONFIG_INTF_STRINGS flag set (except of course that you must specify the dongle's own vendor and product IDs). If you don't feel up to making this change yourself, I can send a patch. Alan Stern -- 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
