On Tue, 12 Apr 2016, John Youn wrote:
> > Wait, even SuperSpeed GEN1-only devices *must* set bcdUSB to 0x0310 ? Do
> > you have a reference to that ? I find that pretty odd because this means
> > that if I take any of my USB3 devices that I already have today, and run
> > them against latest USBCV, they'll all fail and that's not very nice.
>
> Yup, that is exactly what happens. See 9.6.1 in the USB 3.1
> specification. Also the CV tool and compliance test specification from
> USB IF say this as well. If you test with any existing SuperSpeed
> device it will fail.
I have the definite impression that the USB IF is getting more and
more careless as it gets older. The first two paragraphs of 9.6.1 are
actually contradictory!
A device descriptor describes general information about a
device. It includes information that applies globally to the
device and all of the device’s configurations. A device has
only one device descriptor.
The device descriptor of an Enhanced SuperSpeed device shall
have a version number of 3.1 (0310H). The device descriptor of
an Enhanced SuperSpeed device operating in one of the USB 2.0
modes shall have a version number of 2.1 (0210H).
If a device has only one device descriptor, how can it have different
version numbers at different speeds?
Besides, this doesn't say what the version number of a non-Enhanced
SuperSpeed device should be. I don't see why the USBCV would conclude
that a non-Enhanced device needs to set the version to 0x0310.
Alan Stern
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