Setting USB configuration fails

Question

I'm trying to talk to a USB device using libusb, but I feel like I'm tripping up on the first leg of the race. I know precisely what endpoints I need to talk to, etc., but I can't even get that far. I have, in essence:

usb_device *dev = ...; // opened from get_busses()
usb_set_configuration(dev, dev->config[0].bConfigurationValue); // bConfigVal = 1

Now, I can look at the device information in debug mode and I know that the current configuration is 0 (uninitialized / just after restart), and there's exactly 1 valid configuration, which has a configuration number of 1. But when I set the config to 1, I get a return value of -22, which (passed through the stringifier) translates to "windows api error: bad parameter.

I haven't been able to find other people having a similar problem, and it seems like such a simple thing to do -- I can't even claim the interface, or set the alt-interface, or anything like that, because I have to set the configuration first. What am I missing? (if it matters: this is on WinXP)

Answer 1

Looking at libusb-win32\src\driver\set_configuration.c, there seem to be a bunch of different reasons for returning STATUS_INVALID_PARAMETER.

Use libusb_set_debug (from your user mode application) to set verbose debug level, then run Sysinternals DebugView to see the driver's error messages. Hopefully you'd see a clue as to why your set_configuration call fails.