Re: [PATCH 04/14] libata-hp-prep: update ata_scsi_find_dev() and friends

[Tejun Heo <htejun@gmail.com>]

Jeff Garzik wrote:
> Tejun Heo wrote:
>> Separate out ata_find_dev() and __ata_scsi_find_dev() from
>> ata_scsi_find_dev().  ata_find_dev() checks ATA_FLAG_SLAVE_POSS for
>> id==1 case, so all three functions return NULL if id==1 is specified
>> for !SLAVE_POSS port.  These will be used by later hotplug
>> implementation.
>>
>> Signed-off-by: Tejun Heo <htejun@gmail.com>
> 
> ACK with future comment:
> 
> Once we have a better way to sequence simplex + master/slave + normal 
> SATA, libata-scsi should move to exporting one Scsi_Host per controller, 
> with each physical ATA bus being a scsi channel.

I think the 'better way' would be implemented after we move to new block 
infrastructure (libstorage).  libstroage will probably deal with the 
mentioned command scheduling with queue grouping and associated 
scheduling mechanism, and SCSI mapping will be done by SATL.  Although 
mapping port id to channel fits better, I'm not sure whether the 
conversion would be worthwhile at that point. It wouldn't make any 
functional difference but the change would be visible to userspace.

If we're gonna do that, how about piggybacking ataX -> ataX-1 change 
with/around it?  It also is a user-visible change and the magnitude of 
affect on user space would be similar.

-- 
tejun