Re: [PATCH RFC 0/6] libata/scsi/libsas: Allocate SCSI device earlier for ata port probe

[Damien Le Moal]

On 9/21/22 17:24, John Garry wrote:
> On 21/09/2022 05:04, Damien Le Moal wrote:
> > On 9/20/22 19:27, John Garry wrote:
> > > Currently for libata the SCSI device (sdev) associated with an 
> > > ata_device
> > > is allocated when the port probe has completed.
> > >
> > > It's useful to have the SCSI device and its associated request queue
> > > available earlier for the port probe. Specifically if we have the
> > > request queue available, then we can:
> > > - Easily put ATA qc in SCSI cmnd priv data
> > > - Send ATA internal commands on SCSI device request queue for [0]. The
> > >    current solution there is to use the shost sdev request queue, which
> > >    isn't great.
> > > This series changes the ata port probe to alloc the sdev in the
> > > ata_device revalidation, and then just do a SCSI starget scan 
> > > afterwards.
> > >
> > > Why an RFC?
> > > 1. IPR  driver needs to be fixed up - it does not use ATA EH port probe
> > >     Mail [1] needs following up
> >
> > Yes. If IPR could be converted to ata error_handler, a lot of code can 
> > be simplified in libata too.
>
> Hmmm... yeah, it would be good to see progress there.
>
> > > 2. SATA PMP support needs verification, but I don't have a setup
> >
> > Port multiplier behind a sas HBA will be challenging to setup :)
> > I can try, but I will need to open up one of my servers and hook a 
> > small PMP box to one of the pm8001 plugs. I may have the cables for 
> > that... Let me check.
>
> I was more thinking of just AHCI with a port multiplier.

OK. I got confused :)
Easy then, my test box is all hooked up already.
Will give this a spin.

> As for SAS controllers, I don't think it's something to be concerned 
> about. For a start, I know for sure that hisi_sas HW does not support 
> port multipliers, and I don't think that pm8001 does either. In 
> addition, libsas does not even support it - I did see a series in the 
> scsi list from years ago (to support it), but it did not progress.
>
> Thanks,
> John

--
Damien Le Moal
Western Digital Research