On Monday 11 February 2008, Alan Stern wrote: > > 2. What is the "device address" used for in QH? > > There is no "device address" field in a QH -- at least, there isn't in > uhci-hcd or ehci-hcd. Maybe other controller drivers do have such a > field.
There *is* a device address field in EHCI, and also in OHCI. It identifies the specific USB device on that bus. (ISTR that UHCI puts those into TDs.) > > 3. can 2 QHDs point to the same endpoint? > > Ex: QHD[0]--> ep0 > > QHD[1]--> ep0 > > No. Because the QH holds per-endpoint state that gets updated by the controller (at least, in EHCI and OHCI). Like the data toggle used in the next packet to go out, and the contents of the endpoint's I/O queue. - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
