RE: Slightly off-topic, USB code in Linux working, but fails in U-Boot

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On Fri, 14 Feb 2014, Paul Zimmerman wrote:

> > The problem may have something to do with the fact that the keyboard's
> > internal hub runs at full speed.  The other devices you tested, which
> > worked okay, would have been low speed and high speed but not full
> > speed.
> 
> The original email said:
> 
> > The status returned from the hcd is 0x4a (Stalled, XactErr, SplitXState)
> 
> Could the SplitXState be menaingful? Maybe something to do with transaction-
> translator support in u-boot?

No doubt the problem is related to the TT support somehow.  In itself, 
the SplitXState flag doesn't mean much -- just that an error occurred 
while the controller was trying to complete a split transaction.

It probably would be more useful to stick the bus analyzer on the 
high-speed part of the transfer, i.e., between the root hub and the 
internal hub.  I assume this isn't feasible, though.

About the only path forward is to do what Peter suggested: dump the 
QH and qTD data structures to see if they are correct.  For example, is 
the EPS field in the QH set to indicate Full Speed?

Alan Stern

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