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. > >> 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). 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
