2012/4/21 Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>: > On Thu, Apr 19, 2012 at 04:42:04PM -0400, Mike Vlad wrote: >> Hello Sarah, >> >> I've been trying to get answers to some questions from Intel and elsewhere and it proved unsuccessful. Long story short, I discovered you and your involvement in xHCI. I don't know much about hardware/software inner workings, and am looking for a little clarification: >> >> 1a) Can a controller compliant to xHCI rev. 0.96 be updated to 1.0? (i.e. via firmware/bios/Linux kernel update?) > > No, the hardware registers are different. A 0.96 or 1.0 chipset is > certified to that particular specification revision, and the vendor has > no incentive to provide an upgrade. > >> 1b) Or are these revisions hardware based? (Meaning whatever revision it comes with, it has to stay that way) > > Yes. > >> 2) Does it look like there's a revision after 1.0 on the horizon? > > Let me explain what the 0.96 and 1.0 revisions mean before I answer that > question. > >> 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. 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? Best Regards, Elric > > Think of the 0.96 spec as a test run. Intel wanted to make sure the > interface architecture is correct before we allow anyone (including > ourselves) to integrate it into chipsets that are harder to swap out > than a stand-alone chip. > > There were architectural issues that were fixed in the 1.0 spec that > were found in the 0.96 spec. I can't remember too much about what got > fixed though. Some registry tweaks, maybe some bulk streams hardware > behavioral fixes for the new USB storage class, USB attached SCSI (UAS), > and some updates for the USB 2.1 low power states (link PM). > > If Intel were ever to have a "1.1" xHCI spec, it would probably be a > compilation of the errata that's currently available against the 1.0 > spec. But it's not a big leap, like from discrete hosts to integrated > hosts like the 0.96 to 1.0 spec is. > >> I'm looking to buy a 7 series Intel motherboard soon (which complies to rev. 1.0 according to an Intel datasheet for OEMs) and all the ones I wanted have 3rd party USB 3.0 controllers (ASMedia ASM1042) that comply to 0.96, even though the latest is 1.0. So my thinking is that I don't want to get controllers with "old standards" and have a feature(s) missing that I may need in the future when USB 3.0 matures, assuming no updates are possible. > > Back at IDF, Intel announced that our Ivy Bridge chipset (Panther Point) > will have an integrated (1.0) xHCI host controller. If you really want > a 1.0 host, then you should wait for an Ivy Bridge system. > > I'm using a discrete 0.96 NEC xHCI in my personal x220 laptop, but > that's because I'm a crazy early adopter who couldn't wait to get a new > computer with USB 3.0. :) I have to say, I wish I had waited for the > Ivy Bridge ultrabooks instead, since those will be much thinner and > lighter, and have an Intel 1.0 xHCI host. I've been waiting to upgrade > my work laptop until Ivy Bridge comes out, of course. > > Bit of legalize: The above paragraph is designed to express my personal > preference, and should in no way be construed as being the opinions of > my employer, Intel. > > 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 -- 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
