Re: EHCI debug documentation

[Sarah Sharp <sarah.a.sharp@intel.com>]

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.

That comment should be in the documentation for ehci early printks too.

Sarah Sharp