On Mon, 23 Nov 2015, Peter Stuge wrote: > Alan Stern wrote: > > > > > It does print out a message, though not a big one. Would you like it > > > > > to do something more specific? A more verbose "usage" message, > > > > > perhaps? > > > > > > > > That's a good idea, and additionally I think it would be important to > > > > print (much) more information if the ioctl() fails. > > > > > > I agree. > > > > What more is there to print? If the ioctl fails, all the program gets > > back from the kernel is an error code, which it already prints out. I > > wouldn't mind adding something else, if anybody can suggest what it > > might be. > > Information about possible reasons for failure, in particular > that this operation may simply not be supported by the hardware. > > Ideally even have a special case for that, with overly clear text, > if it is indeed possible to determine from the error code that this > is the cause. USB hardware always supports reset. Any device that didn't support it would be unusable. The very first thing that Linux does when it detects a new device has been plugged into a port is issue a reset. The same is true for Windows. Now, lots of other things can go wrong. For example, it may not be possible to disable Link Power Management prior to doing the reset. Or the device's descriptors may change because a firmware update was installed and activated by the reset. Or it may even be something as simple as the device disconnecting from the bus before or during the reset. The error codes don't distinguish among all of these possibilities. Still, I'll see what I can do. 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
