Re: [PATCH] libata: add enclosure management support

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2008-01-18 at 16:55 -0800, Kristen Carlson Accardi wrote:
> On Fri, 18 Jan 2008 18:47:18 -0600
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> 
> > On Fri, 2008-01-18 at 16:35 -0800, Kristen Carlson Accardi wrote:
> > > > Unfortunately, all the dual SAS/SATA enclosures seem to be coming
> > > > with either SGPIO devices or full fledged SES-2 devices.  I've
> > > > actually got both (a backplane with SGPIO and an internal
> > > > SAS/SATA enclosure with SES-2).  Unfortunately, I don't have the
> > > > necessary information to drive the SGPIO one ... it's connected
> > > > directly to an aix94xx using the mini4i SGPIO signals ... I think
> > > > aic94xx can drive them, we just don't have the programming
> > > > information.  The other is a standard SES-2 device, which I think
> > > > I might be able to get working.
> > > > 
> > > 
> > > Having documentation would be pretty helpful :).  I know for ICH8,
> > > if you read the docs it says that it supports SGPIO as well.  But
> > > then you realize it supports SGPIO via the LED protocol, wired up
> > > to translate LED to SGPIO via hardware.  But, even if it did
> > > support straight SGPIO, this design can accommodate that.  Can we
> > > see the documentation for the SES-2 device?
> > 
> > Yes, sure; SES-2 is here (usual place, since it's a SCSI standard):
> > 
> > http://www.t10.org/ftp/t10/drafts/ses2/ses2r19a.pdf
> > 
> > SGPIO is more convoluted.  The canonical link is
> > http://www.sffcommittee.com/ but that just seems to send you back to
> > seagate.  The actual standard is this one:
> > 
> > ftp://ftp.seagate.com/sff/SFF-8485.PDF
> > 
> > James
> > 
> > 
> 
> No, I meant for the actual device.  The specs don't help all that much
> in the area of actually transmitting the messages at the driver level -
> at least they don't for AHCI.

OK, now I'm confused.  A SES-2 device is a SCSI device.  The standard
defines everything for them.  They sit on the bus like any other SCSI
device.

SGPIO is a separate bus; it's also fully defined in SFF-8485, so my
SFF-8485 compliant backplane should be fully defined by the spec as
well.  If you're asking how the SGPIO transciever in the aic94xx works,
that's the piece I don't know ... it's not in the RAZOR spec.

James