On Wed, 11 Jan 2012, Alan Stern wrote: > On Tue, 10 Jan 2012, Sarah Sharp wrote: > > > When a SuperSpeed device is plugged into a high speed hub or an EHCI > > port, it will show up as a high speed device with a BCD of 0x0201 or > > 0x210 and it will contain a SuperSpeed Capabilities BOS descriptor. If > > we see such a high speed device, warn the user that they should plug > > their device into a USB 3.0 hub or xHCI root port. Only warn the user > > if there is at least one SuperSpeed roothub available. > > > > We could attempt to fetch BOS descriptors for low or full speed devices, > > in case the user plugs in a USB 3.0 device into an OHCI or UHCI-only > > port, but it's possible those devices will choke on the request and fail > > to be enumerated. Keep the current behavior of only asking for BOS > > descriptors for devices that advertise a bcdUSB of 0x0201 and above. I forgot to mention this in the earlier email. The logic of this paragraph is wrong; we _do_ attempt to fetch BOS descriptors for low- or full-speed devices. The only requirement is that the bcdUSB value be >= 0x0201, and if that requirement is satisfied then the device shouldn't choke on the request, regardless of its current speed. 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
