2012/2/21 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Mon, 20 Feb 2012, Wizard wrote: > >> >> Yes the ohci-hcd driver know this, while the usb device, such as keyboard >> >> mouse, use this address format? >> > >> > No, that format is used only by the OHCI hardware. USB devices use a >> > similar but different format, described in the USB-2.0 spec (see Figure >> > 8-5). >> > >> You mean the Figure 8-5, Token Format. > > Right. > >> PID, ADDR, ENDP, CRC5 >> 8 7 4 5 >> >> Hmm... this just looks like the fields in the ED. >> ADDR <-> FA >> ENDP <-> EN > > As I said, it is similar but not the same. For example, in the ED the > low-order bit of EN is adjacent to the high-order bit of FA, but in the > Token packet it is the other way around. Also, the ED has no CRC > field. > >> And I think the Token Packet is sent in the hardware? > > Yes. > >> This is seen by the device driver? > > No; it is seen only by the hardware. > Thanks for your explanation. I learned a lot from you. > Alan Stern > -- Wizard -- 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
