Reminder> SAS PHY working group conference call Thursday, 8 am PDT

Alvin.Cox at Alvin.Cox at
Tue Jun 13 14:03:30 PDT 2006

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1.	Training sequence/speed negotiation
The following ideas are for consideration. Please investigate and discuss 
on the 6/15 call. Reflector traffic is welcome and encouraged. Some 
concerns related to how the information is handled and whether it reaches 
beyond the PHY layer.
Idea floated in the WG meeting of just sending G1 traffic in the G3 
window.  This should get through without needing training.
It would diverge from the normal window definition by:
* Start with training pattern? (Suggest leaving as idle time since speed 
will be determined later)
* Continue with ALIGN (0)/ALIGN (1) algorithm like today
* End by sending information about supported rates and features, not just 
sending ALIGN (1)s.  Include:
  - Additional rates supported (G3, G4, G5, etc.)
  - Whether the phy can receive SSC
  - Advice to the other transmitter to help it decide about tx amplitude, 
preemphasis, etc.
    * "Receiver device" characteristics (which it should know)
    * System interconnect characteristics (which it may know)
This would be the last trial window; there'd be no need for subsequent 
(G4, G5, etc.) windows following the current algorithm. The next window 
would be the final one, which would enable SSC if supported, start with a 
training sequence, perform whatever is needed for dword sync, etc. like 
has been discussed.  If lock is unsuccessful, the phys restart OOB.  If 
lock is repeatedly unsuccessful, turn off the fastest rate and try again. 
(Same issues as today)
2.	Spread Spectrum Clocking 
a. SSC options / trade-offs [Witt]
Compares up-, center- and down-spreading for SSC. Conclusion was that the 
short-term buffering impact of SSC is minimal, but long-term impact was 
not covered. Makes a possible case for center-spreading.
b. SAS-2 Spread-spectrum clocking by upspreading (06-263) [Elliott]
Present cases and issues with different SSC schemes. Supports 
up-spreading, but it looks like the center-spreading calculation may have 
not been done correctly regarding the buffer dword total. Kevin Witt will 
contact Rob about this. 
Toll Free Dial in Number: (866) 279-4742 
International Access/Caller Paid Dial In Number: (309) 229-0118 
Webex information: 
Topic: SAS-2 PHY WG 
Date: Thursday, June 15, 2006 
Time: 10:00 am, Central Daylight Time (GMT -05:00, Chicago) 
Meeting number: 826 515 680 
Meeting password: 6gbpsSAS
Alvin Cox
Seagate Technology, LLC
Tel 405-350-7424
Cell 405-206-4809

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