2012/4/24 Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>: > On Sat, Apr 21, 2012 at 10:53:04PM +0800, Elric Fu wrote: >> 2012/4/21 Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>: >> > On Thu, Apr 19, 2012 at 04:42:04PM -0400, Mike Vlad wrote: >> >> The thing I don't understand is what xHCI really is, in simple terms. A driver? A hardware architecture? >> > >> > xHCI is a spec that defines the interface between the eXtensible Host >> > Controller (xHC) and software. So it's an interface specification, that >> > defines both the registers that the hardware needs to expose, and the >> > data structures and behavioral model that a software driver needs to use >> > in order to communicate with the hardware. >> > >> > Basically, the 0.96 spec was released to allow third-party host vendors >> > to create PCIe add-in cards or stand-alone chips that OEMs could add to >> > their motherboard. You can only integrate an xHC into a chipset (making >> > the hardware physically part of the chipset package) if you comply with >> > the xHCI 1.0 spec. >> >> Hi Sarah, >> >> I am a little confused. Thanks for your explanation. Actually, I never >> heard the differences between 0.96 and 1.0. I always thought 0.96 >> was draft spec and 1.0 was official spec. > > If you search the 0.96 spec, you won't find the word "draft". There > were draft specs before 0.96, like the 0.95 draft spec. > > The 0.96 spec was the first official xHCI specification that hardware > vendors could certify hardware against. I think they can even still get > USB-IF certification for 0.96 hosts, but I could be wrong. > >> So I have a question about >> it. Do you mean that the xHC adhere to xHCI 1.0 spec can't be PCIe >> add-in cards or stand-alone chips? I know some vendors produce >> stand-alone chip complies with xHCI 1.0 spec, such as NEC >> µPD720201. Did I make a mistake? or those chips don't strictly comply >> with xHCI 1.0? > > Companies can still make an xHCI 1.0 host that is a discrete chip. > Nothing about the 1.0 spec stops them from doing that. They just can't > make a 0.96 host that is integrated in a chipset. Got it. I made a mistake. Thank you for your answering. Best Regards, Elric > > Sarah Sharp -- 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
