From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <1df49ca90762af86ffcb01ec2f50ea44@proxima.alt.za> To: 9fans@cse.psu.edu Subject: Re: [9fans] TODO lists for Plan 9 Date: Fri, 9 Jul 2004 11:25:43 +0200 From: lucio@proxima.alt.za In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Topicbox-Message-UUID: bae264e6-eacd-11e9-9e20-41e7f4b1d025 > I'm afraid that I am serious about USB 2 needing OCHI code (unless the > OCHI interface is compatible with the UCHI interface, but I can't > believe we'd be so lucky with PC hardware). I haven't been tracking > USB recently, so I hadn't heard about 2.1 and ECHI, but my > understanding is that UHCI can only drive USB 1 devices, and that USB > 2 devices require OHCI interfaces to get the increased speed (480Mb/s > for 2.0 also). I suppose one could look at the *BSDs to see how > different the various USB interfaces are. As I read the spec, a 2.0/2.1 (maybe I got this last one wrong - in fact, it is USB 1.1 and USB 2.0) controller has to be able to address 1.1 devices and it seems that implementations do this by providing a 1.1 controller (OHCI seems to be the norm, I don't think it is superior to UHCI) as well as a 2.0 controller. The latter is apparently EHCI exclusively. I have only encountered this on PCI buses where it seems to me that the OHCI device stands independently of the EHCI one. As for getting clever, I think the desire to spawn new industries dovetails too well with the idea of standardising everything and the kitchen sink into a single norm. Thus simplicity is not the objective. At least not until the economics change. ++L