Re: EHCI debug documentation

[Greg KH <gregkh@suse.de>]

On Wed, Mar 04, 2009 at 04:59:28PM -0500, Alan Stern wrote:
> On Wed, 4 Mar 2009, Eric W. Biederman wrote:
> 
> > Greg KH <gregkh@suse.de> writes:
> > 
> > > * Randy Dunlap <randy.dunlap@oracle.com> wrote:
> > >> Yinghai Lu wrote:
> > >> > b. netchip USB debug cable
> > >> 
> > >> http://www.plxtech.com/products/NET2000/NET20DC/default.asp
> > >
> > > I have reports that the newer version of this device does not work on
> > > Linux as it isn't enumeratable as a "real" usb device on one end.
> > >
> > > I don't have one of these new devices yet to test it out, has anyone
> > > else heard of this problem?
> > 
> > With the first generation of devices I remember they were peculiar and
> > finicky.  I don't recall the exact details but I remember the devices
> > able to get into weird states that may resemble what you describe.
> 
> Those devices were a little peculiar in that they were powered only on
> one side.  That is, they would take bus power only from the right-hand
> connector (looking at the face with the PLX logo).  So if you plugged
> in only the left side, the device would not show up or enumerate.  But 
> if you plugged in both sides, then both of them would enumerate okay.

Thanks for the information, I'll try to get the person that reported
this to retest and see if both sides plugged in at the same time works
better.

greg k-h