On Sun, 28 Dec 2008, Erik Ekman wrote: > > Please attach to the bug report some usbmon traces showing what happens > > when you try to use the fingerprint reader more than once: one trace > > with this commit present and one with the commit dropped. Instructions > > for usbmon are in the kernel source file Documentation/usb/usbmon.txt. > > > > Alan Stern > > > > I have now uploaded two usbmon logs. These logs show you running the program twice? The time gap between the two runs is no longer than 2 ms! That's certainly not what I would expect. Have you tried something more reasonable, like a second or longer? There's no difference between the logs corresponding to the behavior you described. The interaction between the program and the device in the short log is the same as in the long log, right up until the time the short log ends. In more detail: The two logs begin the same. The first program run ends with a 64-byte bulk-IN transfer from the device. After that the "reverted" log shows a Set-Interface request; the vanilla log doesn't include this request because the commit prevents it from being sent. But this is invisible to the program, since it occurs after the first run and before the second run. Then the program was started again (after a _very_ short delay) and both logs show a Set-Config request followed by a 1-byte Vendor-specific control-OUT transfer. This same pair of requests also occurs at the beginning of both logs, which confirms that it marks a new start of the program. Both the Set-Config and the control-OUT succeeded. Then the "reverted" log shows the program going on to send a bulk-IN request and do more bulk transfers, whereas the "vanilla" log shows no more activity. Clearly this has nothing to do with the presence or absence of the Set-Interface request; the program has no way to know whether or not that request was sent because it receives the same information from the device in either case. In short, the "vanilla" log shows the second program run stopping short for no apparent reason. There is no evident connection with the commit you identified. 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
