2012/2/20 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Sun, 19 Feb 2012, Wizard wrote: > >> 2012/2/19 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: >> > On Sat, 18 Feb 2012, Wizard wrote: >> > >> >> All >> >> >> >> I am reading the OHCI specification( seems a little bit old). >> > >> > Yes, it is old. The current version dates back to 1999. The UHCI spec >> > is even older (1996). >> These two are version 1.0 and 1.1, I think. >> EHCI is for 2.0, right? > > OHCI and UHCI support USB-1.1. EHCI supports USB-2.0. > Thanks for your clarification. >> >> In Section 4.2, Endpoint Descriptor Format, there is the EN and FA in DWORD0. >> >> >> >> So these two combined forms the Endpoint address right? >> > >> > Well, they form the address that the hardware has to use in order to >> > send a packet to the endpoint. That's not what we usually mean when we >> > talk about the "endpoint address". >> > >> >> >> While this is the hardware address, not visible in driver? >> > >> > I don't understand your question. Of course these fields are visible >> > to the driver. If the ohci-hcd driver didn't set these fields >> > correctly, the hardware wouldn't work. >> > >> Thanks Alan. >> >> 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. PID, ADDR, ENDP, CRC5 8 7 4 5 Hmm... this just looks like the fields in the ED. ADDR <-> FA ENDP <-> EN And I think the Token Packet is sent in the hardware? This is seen by the device driver? > 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
