On Fri, 8 Jul 2011, Graeme Gill wrote: > Alan Stern wrote: > > Hi Alan, > thanks for your comments. > > > A little, not much. It looks like on the ASRock P67 system, the > > low-speed device is attached through a hub, probably to a high-speed > > controller, whereas on the ThinkPad X40 the device is attached > > directly. The hub itself behaves a little oddly because it doesn't > > report the connection as low-speed until the port has been enabled. > > Is this the so-called "rate-matching" hub that Intel is using in their > > more recent chipsets? > > I've had more frequent reports of this problem with recent systems. > > > That's consistent with the P67's internal hub not working right. Can > > the user check whether an ordinary USB keyboard (one without an > > internal hub) works with that computer? > > > Also, can the user get hold of a USB-2.0 hub and place it between the > > P67 and the device? Then the Transaction Translator in the external > > hub would be used instead of the TT in the internal hub. > > I'll ask. > > > Going back through earlier messages in this thread, I see this has > > already been tried and it works. Also the device works on the P67 if > > the program resets the interrupt endpoint before each read after the > > first. > > Sorry, there are several different situations, all with similar symptoms. > > By default the code always does a resetep before each data read on Linux. > The device doesn't work without this on Linux on any hardware I know of. > There are certainly examples of the same hardware running MSWin not > needing resetep's (in fact they fail if resetep's are used). > > On my test machine, it fails with very similar symptoms to those > described by the user with the ASRock P67 if I use an external > USB 2.0 hub to connect the device to my system. Once again, the external > hub causes no problems when the system is running MSWin. > > With some hardware running Linux (like the ASRock P67), it doesn't seem > to work at all under Linux. This sounds like a very difficult problem to pin down without hardware assistance. I've got a bus analyzer; is it possible for you to loan me one of these devices for testing? 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
