Subject: Re: Ehci/Umass bug ?
To: Lennart Augustsson <>
From: Charles M. Hannum <>
List: tech-kern
Date: 11/25/2004 09:24:42
On Thursday 25 November 2004 08:44, Lennart Augustsson wrote:
> Vincent wrote:
> > Hi,
> >
> >> BABBLE certainly means the device is talking when it shouldn't.
> >> It could be a consequence of the earlier XACTERR, maybe.
> >
> > What does that XACTERR mean ?
>  From the EHCI spec:
> "Set to a 1 by the Host Controller during status update
> in the case where the host did not recieve a valid response
> from the device (Timeout, CRC, Bad PID, etc).  This bit will
> only be set for IN transactions."

Unless you have a bad cable, it's usually caused by a "bad PID" -- which 
typically means the data toggle is in the wrong state.

There are some weird cases that can cause this to happen under normal use 
(IIRC, aue can cause it by doing a control transfer while there's an 
outstanding bulk transfer queued).  I've thought about how to fix this all 
cleanly, but it's a pain.

As for what's wrong with this particular device, I haven't looked at it in 
detail.  :-)