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Date:      Wed, 6 Oct 1999 13:11:46 -0700 (PWT)
From:      Matthew Jacob <mjacob@feral.com>
To:        "Justin T. Gibbs" <gibbs@narnia.plutotech.com>
Cc:        Vadim Belman <voland@plab.ku.dk>, scsi@FreeBSD.ORG
Subject:   Re: 'Unexpected busfree'
Message-ID:  <Pine.LNX.4.04.9910061311030.1525-100000@feral.com>
In-Reply-To: <199910061823.MAA25143@narnia.plutotech.com>

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> In article <85k8p2vvmt.fsf@eagle.plab.ku.dk> you wrote:
> > 	I wonder if someone can tell me: what kind of error is the
> > 	following?
> > 
> > Unexpected busfree.  LASTPHASE == 0x0
> > SEQADDR == 0x5e
> > 
> > 	And what do I do with it?
> 
> This means that the bus appeared to go free during the middle of a
> transaction.  In this case, it happened during a DATAOUT phase.
> Essentially the target hung up without saying good bye first.
> 
> These kinds of problems can be caused by bad cabling setups.  Perhaps
> the REQ/ACK offset counters got out of sync (initiator did not see a
> REQ pulse) so the target timedout and ended the connection.  It's hard
> to say without an analyzer.  Be sure to use forced perfect terminators,
> high quality cables, and don't exceed 3m in cable length.

Also, for some older peripherals I've found that if they detect a parity
error when receiving data they just drop off the bus rather than go to the
bother of completing the command first.




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