Subject: RE: SAS2 SNW-3 SP29:SAS_Train
Date: Wed, 24 Jan 2007 08:53:25 -0600
From: "Elliott, Robert (Server Storage)" <Elliott@hp.com>
To: <t10@t10.org>
X-Message-Number: 7512
Formatted message: HTML-formatted message
Attachment #1: smime.p7s

That state is waiting for the SP receiver to report Training Completed
(meaning the receiver itself is satisfied with the incoming data stream),
not that it has detected any particular incoming TRAIN or TRAIN_DONE
(indicating the state of the other phy).
Training Completed is in the list of messages defined earlier in the
proposal, but is never used again; it was supposed to have been used here.
That correction will be incorporated into sas2r08.
  _____  
From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Craig Stoops
Sent: Tuesday, January 23, 2007 4:24 PM
To: t10@t10.org
Subject: SAS2 SNW-3 SP29:SAS_Train
Steve, Rob and other interested parties,
Per the latest 6Gb SNW-3 proposal pasted below, the TRAIN Completed message
is not defined in the document. Based on my read of other parts, I think
this should be "TRAIN Transmitted message" as the requirement per
6.7.4.2.3.3 is to send at least 1 TRAIN pattern and after achieving receiver
sync, then transition to sending TRAIN_DONE. 
6.8.4.12.4 Transition SP29:SAS_Train to SP30:SAS_TrainingDone
This transition shall occur if:
a) this state receives a TRAIN Completed message before the TLT timer
expires; and
b) dword synchronization is acquired.
Second point - becuase one end device may be capable of acheiving rx sync
faster than the other, it is possible (as seen by our modeling) for the
slower device to be in SP29 and before that device gains sync the faster
device starts sending TRAIN_DONE.
So it can not be a condition of SP29 -> SP30 to receive a TRAIN pattern, but
rather either TRAIN or a TRAIN_DONE pattern This is implied by aquiring
receiver synchronization.. Currently, as it is undefined, some people may
consider the TRAIN Completed message to be TRAIN Received messsage.
I think it should be further clarified, as I beleive was the original
intention, that both TRAIN and TRAIN_DONE serve to allow a receiver to gain
synchronization. If true, then the slow device will transition from SP29 to
SP30 when gaining rx sync even though it is receiving TRAIN_DONE and not
TRAIN.
Basically, in summary, rewording 6.8.4.12.4 to:
  This transition shall occur after:  
    a) Transmitting at least 1 complete TRAIN pattern (or said the spec way,
after having received at least one TRAIN Transmitted message)
   b) Receiver DWORD synchronization is acquired
Thoughts?
Craig Stoops
ExpertIO, Inc
www.expertio.com
805-428-0839