Re: [PATCH] ieee1394: sbp2: pass REQUEST_SENSE through to the target

[Douglas Gilbert <dougg@torque.net>]

Stefan Richter wrote:
> Delete some incorrect code, left over from the initial driver submission
> in March 2001.
> 
> SBP-2 targets should provide sense data via the SBP-2 status block
> (autosense).  We have to pass the REQUEST_SENSE command through to
> targets which don't implement autosense, if there are any.

Umm, REQUEST SENSE has several other useful capabilities.
It can convey information about low power conditions,
a progress indicator (e.g. during FORMAT with IMMED=1)
and informational exception warnings. It is also
defined to work any time INQUIRY works (e.g. on lun=0
when there is no lu there but there is a lun>0).

smartmontools sets MRIE to 6 in the control mode page so
it can periodically poll a disk with REQUEST SENSE to see
if it has tripped a threshold . It could use other techniques
but they would most likely interfere with normal error
processing on the host OS (and linux is one of about 8).

So, this patch is a step in the right direction.
Hopefully not too many other LLDs are playing
games with REQUEST SENSE.

Doug Gilbert

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