SAS SMP PHY CONTROL function: PPTV and programmed link rate fields

Gerry.Houlder at seagate.com Gerry.Houlder at seagate.com
Wed Jan 22 07:24:31 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* Gerry.Houlder at seagate.com
*
I prefer option 3.

However I don't think the DISCOVER function needs to set the bits if the
fields are writeable. If the fields are not writable the "target" end will
just ignore whatever is sent in those fields and use the predetermined
value. If they are writeable the target should round the value sent to the
nearest supported value if the exact value is not supported. This kind of
rounding rule is already described in SCSI. The initiator can discover
whether rounding is occurring (or if the value is even changeable) by doing
DISCOVER after the PHY CONTROL operation.

>3. Add "set xyz field" bits
>
>Add "Set PPTV" and "Set Programmed Link Rates" bits in byte 11.
>Regardless of Phy Operation, honor the associated fields if the
>corresponding Set bit is one; ignore them if the Set bit is zero.
>
>The DISCOVER function would return these bits in byte 11 set to 1 if the
>target supports those as writable fields.



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