usb info

[Mark Knecht]

On 7/13/05, Rick Stevens <rstevens at vitalstream.com> wrote:
> Mark Knecht wrote:
> > On 7/13/05, Chuck Lawrence <CELawrence at lbl.gov> wrote:
> >
> >
> >>1.  how can I determine, with some certainty, whether the bus is 1.1 or 2.0?
> >
> >
> > cat /proc/bus/usb/devices and look at the "Ver=" entry. From my Gentoo
> > laptop. Note: The driver is also a good clue, I think. ehci is 2.0.
> > ohci is 1.1.
> 
> Yes, but the dead giveaway is shown in your listing, marked by me:
> 
> >
> > flash ~ $ cat /proc/bus/usb/devices
> >
> > T:  Bus=05 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh= 5
>                                                      ^^^^^^^
> <snip>
> 
> "Spd=480" is 480Mbps and that's USB2.  If it said "Spd=12", NOW you've
> got USB1.1 (12Mbps), and now you know why they say USB2 is 40 times
> faster than USB1.1 (480/12 = 40).  Simple, no?

Yes, absolutely simple, and AFAIK 100% correct for USB controllers,
but not necessarily for devices. There are some devices which are USB
2.0 compatible but not 480Mb/S. The example I gave was a controller
since I don't own any USB 2.0 devices. All my high-speed devices are
1394.

Anyway, small points. All of these should work most of the time.

Cheers,
Mark