On 4/13/2016 7:58 AM, Alan Stern wrote: > 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. Non-Enhanced SuperSpeed (i.e. HS and lower) devices follow the USB 2.0 spec. Or do you mean SuperSpeed-only devices? In the 3.1 spec, "Enhanced SuperSpeed" means either SuperSpeed (Gen 1) or SuperSpeedPlus (Gen 2). So they should set bcdUSB to 0x0310 as well. John -- 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
