Doubt in SAS speed negotiation sequence

Penokie, George George.Penokie at lsi.com
Tue Sep 17 11:41:58 PDT 2013


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Pooja,
The flow chart is correct. After the device goes through SNW-1 and SNW-2
there are three possible outcomes: go to Final-SNW, go to SNW-3, or end the
speed negotiation .
1-	If the SNW-1 negotiation was valid and the SNW-2 negotiation failed.
That means the agreed to speed is 1.5 Gbps and the Final-SNW occurs.
2-	Any other combination requires another decision to decide what should
happen next.
3-	This decision is not based on if a negotiation failed or was
successful it is based on whether any negotiation occurred or did not occur.
a.	 if there was no SNW-1 negotiation and there was a  SNW-2 negotiation
then the phy ends the speed negotiation sequence without progressing to
SNW-3, transmits negotiation idle, and ignores the SNW information received
during SNW-3.
b.	If there was a SNW-1 negotiation and there was a  SNW-2 negotiation
then the phy moves to SNW-3
c.	 If there was a SNW-1 negotiation and there was a  no SNW-2
negotiation then the phy moves to SNW-3
d.	there was no SNW-1 negotiation and there was a	no SNW-2 negotiation
then the phy moves to SNW-3
Bye for now,
George Penokie
LSI Corporation
3033 41 St NW
Rochester , MN 55901
507-328-9017
george.penokie at lsi.com
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Pooja Gupta
Sent: Tuesday, September 10, 2013 4:20 AM
To: t10 at t10.org
Subject: Doubt in SAS speed negotiation sequence
Hi,
Section 5.10.4.2.4 "SAS speed negotiation sequence" of SPL-3 (Revision 02, 16
January 2013)
describes SAS Speed Negotiation sequence as:
[cid:image001.png at 01CEB3A8.CEC5A4E0]
Here, I am not able to understand the difference between the two yellow
Diamond decision boxes.
I feel that, both result in the same condition of SNW-1 being valid and SNW-2
being invalid.
Can you please help me	understand this.
Regards,
Pooja



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