On Mon, 21 Sep 2009, Sarah Sharp wrote: > > Alternatively when switching configurations or altsettings, you could > > temporarily reserve the maximum of the old and the new bandwidths. > > Then after the switch succeeded or failed, you could release any > > excess bandwidth. > > Good suggestion, however, that won't work with the xHCI hardware. The > xHCI hardware representation of a USB device includes 31 physical > endpoints, and the bandwidth code indicates which of the 31 endpoints > were added, dropped, or changed. The endpoint address is used as an > index into the xHCI device representation. So you can't have the same > endpoint address with two different bandwidth reservations. You don't need to have two different bandwith reservations; you only need to reserve the maximum. However this might not work if the hardware distinguishes between interrupt and isochronous types and the same endpoint has different types in the different settings. 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
