Re: usbtest tests on USB 2.0 full speed device

On Sun, 22 Apr 2007, Hamish Moffatt wrote:

> > Now I'm getting confused.  Your driver runs on the device and usbtest 
> > runs on the host.  How can the host get confused about the device's speed, 
> > and what could your driver possibly do to confuse it?
> 
> I don't know? All I know is that usbtest.c reports that the device speed
> is unknown, in the probe routine. This shows up as follows when I run
> the testusb program;
> 
> unknown speed   /proc/bus/usb/002/013

That line is printed by testusb, not by usbtest.  In fact, if you look at 
the source code for testusb, in the find_testdev() routine you'll see a 
comment:

		// FIXME ask usbfs what speed; update USBDEVFS_CONNECTINFO
		// so it tells about high speed etc

The program prints out "unknown" because it doesn't try to find out what 
the speed actually is.


> /proc/bus/usb/002/013 test 0,    0.000003 secs
> /proc/bus/usb/002/013 test 1,    0.002860 secs
> [...]
> 
> > Furthermore, there's no way for usbcore on the host to leave the speed set 
> > to UNKNOWN.  Look at the code in hub_port_wait_reset() in 
> > drivers/usb/core/hub.c.
> 
> It's only usbtest that's reporting unknown speed. Other messages from
> the kernel seem to be as expected.  Here's what I get on the host with 
> CONFIG_USB_DEBUG;

> Apr 21 17:15:19 snake kernel: usbtest 2-3:3.0: Linux gadget zero
> Apr 21 17:15:19 snake kernel: usbtest 2-3:3.0: full speed {control in/out bulk-in bulk-out} tests (+alt)

That last line _is_ printed by usbtest, as you can easily see.  It doesn't 
look confused in any way, and it reports the correct speed.

Alan Stern


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