Completion of TRAIN or TRAIN_DONE sequences

Mehul Kumar mehul at
Wed Feb 20 10:52:22 PST 2008

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Hi Geoff, 
Well the interpretation is that after the undergoing transmission is
finished, switch to the next. 
Mehul Kumar
- Perfectus Technology Solutions
-----Original Message-----
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Geoff
Sent: Tuesday, February 19, 2008 6:25 PM
To: t10 at
Subject: Completion of TRAIN or TRAIN_DONE sequences
Hello all,
I have a question regarding a possible ambiguity in the SAS-2 spec at
It says:
"If the phy's receiver is trained and acquires dword synchronization
before TLT, then the phy shall stop transmitting TRAIN patterns and
start transmitting TRAIN_DONE patterns."
It also says that upon transmitting 4 or more TRAIN_DONE patterns and
receiving the minimum 1 TRAIN_DONE before MTT,
"then the phy shall:
a)	 stop transmitting TRAIN_DONE patterns;
b)	 start transmitting dwords from the link layer; and
c)	 consider the Train-SNW to be valid."
When it says "stop transmitting" is the intention that TRAIN and
TRAIN_DONE patterns always be sent in their entirety (primitive sequence
followed by 58 scrambled dwords) before switching to the next item, or
may the phy interrupt whatever TRAIN/TRAIN_DONE sequence it is in the
middle of transmitting to switch to transmitting the next item?
-Geoff Hibbert
-Finisar Corporation

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