[mdlug] 1.1 speeds from 2.0 USB pci card

[Dan Pritts]

On Thu, Jan 29, 2009 at 12:32:35AM -0800, Michael S. Mikowski wrote:
> This rings a (distant) bell.  Is it a "high-speed" 2.0 card?  If it is only 
> "full-speed", (s)he might be stuck.  I can't give you anything definitive, but

his original message lists "480mbit/sec" spec on the card from syba

> Given the information, it appears impossible to tell if the controller is "Hi-
> Speed" or not.  However, it really looks like the OS is not treating it like 
> 2.0 (sorry if this is painfully obvious already):
> 
> 00:0a.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1
> Controller (rev 62)
> 00:0a.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1
> Controller (rev 62)

I'd bet this is the onboard controller

> 00:0a.2 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 65)

I'd bet this is the card he added


Michael Rudas said:
> I think what you have is a perfect storm of dodgy drivers, a slow
> processor (600 MHz tops),  and a relatively primitive PCI hardware
> interface.   There's just not enough bandwidth available for USB 2.0,
> I think--which is one reason why they waited until later to implement
> it.

A standard PCI bus provides 1056 mbits/sec (about 133Mbytes/sec)
of bandwidth.

32 bits * 33MHz.

USB2 is nominally 480mbit.

you won't ever get that out of USB even on the fastest system, and
USB transfer rate is dependent on processor speed, so as you surmise
the CPU matters.

that said, there's no way the hardware isn't capable of more than
12mbit (usb 1.1 speed).

it could be a buggy driver; it could be a usb1.1 hub in the middle.
It could even be a device that doesn't do usb2.  I bought a CF card
reader about a year ago that was usb1.1.  bastards.

See what lsusb says.

Are you sure you're really only getting usb1.1 speed?  

danno
--
dan pritts
danno at umich.edu
734-929-9770