On Wednesday 27 June 2012 17:28:30 Alexander Motin wrote:
> On 06/27/12 18:17, Hans Petter Selasky wrote:
> > On Wednesday 27 June 2012 17:08:29 Alexander Motin wrote:
> >> umass problem
> > 
> > Hi,
> > 
> > Are you verifying the received data length for the SCSI commands reading
> > out various data?
> Mentioned revision beyond others adds check for the sense data length in
> case of error. It won't even look into the sense data if reported amount
> (sense_len - sense_resid) is zero or less then needed. I have no idea
> how USB calculates resid, but it may be a problem in this case. I think
> it could be useful to get USB packets trace to see whether it is device
> doesn't return any sense data, or umass improperly interprets them in
> this case for some reason.


The residue is part of the 13 status bytes in the SCSI BOT protocol. If this 
field is zero, the umass driver will compute the residue from the actual data 
transferred as a workaround.

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