On Thu, 2010-11-25 at 09:50 +0100, Gerd Hoffmann wrote:
> On 11/25/10 09:46, Benjamin Herrenschmidt wrote:
>
> > So far tho, it appears that I can (at least with scsi-disk) rely on
> > always been eventually called with SCSI_REASON_DONE so my code (and
> > maybe the usb-msd code too, I haven't verified) relies on that to
> > complete requests... Is that incorrect ?
>
> Yes.
Well, so far it works :-) But I suppose I must be lucky.. I must admit
that it's very unclear how that SCSI "stack" is meant to be used from
the HBA standpoint.
Right now, I've somewhat come up with:
- client request occurs
- call device send_command()
- if result is 0, assume my complete() was called with
SCSI_REASON_DONE
- else, use sign of result for transfer direction, store the
absolute value as the total expected transfer len and call
the device scsi_data_read()/write() and wait for complete()
- when complete() is called:
- if SCSI_REASON_DONE, complete client request
- else perform the client "DMA" for "arg" bytes
- call the device scsi_data_read()/write() again
So far it seems to work with scsi-disk but maybe I miss something in
which case I would very much enjoy being corrected :-)
Cheers,
Ben.
