On Tue, Aug 14, 2007 at 05:23:04PM -0400, Alan Stern wrote:
> On Tue, 14 Aug 2007, Rogier Wolff wrote:
>
> > On Tue, Aug 14, 2007 at 10:23:27AM -0400, Alan Stern wrote:
> > > > The other external disk (also claimed to be full speed) seems to
> > > > achieve
> > > > transfer speeds of 20-30 KB which seems OK.
> > >
> > > If 400 KB/s is bad, how come 20-30 KB/s is OK?
> >
> > He probably means 20-30 M byte/sec.
>
> How could a full-speed device possibly transfer data at 20-30 MB/s?
Because consumers confuse full speed (12) and high speed (480).
> When it comes to ports, the situation is even more confusing. By
> definition, any port (on a computer's root hub or on an external hub)
> that conforms to the USB 2.0 spec must be able to run at high speed.
> So if "the USB comittee", whoever they are, decided to call a port that
> doesn't suppport high speed a USB 2.0 port, they did so in violation of
> the spec.
Hmm. ok. Then those computers I was talking about should be advertised
as having some USB2.0 and some USB 1.1 ports. Fine. Maybe that's the
case.
> Or that ehci-hcd simply wasn't loaded. Maybe you didn't notice, but
> none of the buses in Wim's usbview listing supported high speed.
No, I didn't notice... :-)
My workstation upstairs shows:
|
|- UHCI Host controller
|
|- UHCI Host controller
|
|- UHCI Host controller
|
-- UHCI Host controller
| |
| |- ALTERA IO BOARD 2.0
| |
| -- USB HUB
| |
| |- CanoScan
| |
| |- USB <-> Serial
|- EHCI Host controller.
Which means that I can connect a fast (highspeed) device to the wrong
port and have it perform badly.
And yes, you're right that the EHCI driver needs to be loaded before
reasonable performance is possible.
Roger.
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