[sane-devel] Additional SCSI status?

[abel deuring]

Douglas Gilbert wrote:
> 
> abel deuring wrote:

> > ... and now I have checked, what target status == 2 means: CONDITION
> > MET, says the SCSI 2 draft. So, sanei_scsi_req_wait should not return an
> > error. The only puzzling thing is that driver status is non-zero; the
> > corresponding #defines in linux/scsi/scsi.h are SUGGEST_RETRY and
> > DRIVER_SENSE...

Doug and, Dave

...the stuff above was again nonsense. I was really too tired
yesterday... 2 means check condition...

> >
> > You could try to simply ignore the driver status in sanei_scsi_req_wait.
> > Lines 2191ff are currently:
> >
> > /* status bits INTERMEDIATE and CONDITION MET should not
> >    result in an error; neither should reserved bits
> > */
> > else if (   ((req->sgdata.sg3.hdr.status & 0x2a) == 0)
> >          && (req->sgdata.sg3.hdr.host_status == SG_ERR_DID_OK)
> >          && (req->sgdata.sg3.hdr.driver_status == SG_ERR_DRIVER_OK))
> >   status = SANE_STATUS_GOOD;
> > else
> >   status = SANE_STATUS_IO_ERROR;
> >
> > Replacing this with
> >
> > else if ((req->sgdata.sg3.hdr.status & 0x2a) == 0)
> >   status = SANE_STATUS_GOOD;
> > else
> >   status = SANE_STATUS_IO_ERROR;
> >
> > might work.
> >
> > Doug, can you tell us, when and why SUGGEST_RETRY and DRIVER_SENSE are
> > set?
> 
> Abel,
> The sg driver just sends back what it gets. As noted in the
> sg documentation ( http://tldp.org/HOWTO/SCSI-Generic-HOWTO/x255.html )
> the 'status' (and 'masked_status') fields are sometimes cleared
> even though the sense_buffer is valid. The appropriate condition is:
> 
>    if ((sg3.hdr.status & 0x2) ||
>        (SG_ERR_DRIVER_SENSE == (sg3.hdr.driver_status & 0xf)))
>          /* then the sense_buffer is valid */

Ok, that's one more point to be added to a rewrite of sanei_scsi, as it
would be to return something like SANE_STATUS_RETRY to the backend, if
that's suggested by the OS. But for the current sanei_scsi layer, I
don't see any way to fix Dave's problem without breaking compatibility
with other backends. 

Abel