Reminder: SAS PHY teleconference, 10am CDT, July 20,2006

Alvin.Cox at seagate.com Alvin.Cox at seagate.com
Mon Jul 17 15:26:40 PDT 2006


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Next conference call July 20, 2006 

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Topic: SAS-2 PHY WG 

Date: Thursday, July 20, 2006 

Time: 10:00 am, Central Daylight Time (GMT -05:00, Chicago) 

Meeting number: 826 515 680 

Meeting password: 6gbpsSAS

Agenda: Speed negotiation sequence

During the face-to-ace meeting in Colorado Springs, a new proposal for the 

G3 window was introduced that uses an out of band communication to 

broadcast PHY capabilities. This method preserves the existing speed 

negotiation window structure without depending on G1 or G2 capability to 

work in future generations. I have provided a preliminary list of 

considerations concerning 05-397r5 in the meeting minutes and have 

included them below. There has also been a proposal posted on the T10 site 

concerning how the out of band data could be configured. We will discuss 

these proposals and concerns during the call (limited to approximately 2 

hours)

Uses OOB at 1.5Gbps with a 9uS idle and a 10uS initial burst to "start the 

clock". The 59 10uS intervals start from the far end of the 609uS standard 

window. Later this was changed to a 10us idle at the end and 58 intervals 

for data.

Since OOB already requires the 1.5Gbps bursts, this proposal has a subset 

of the existing OOB requirement and is actually less demanding because of 

the relatively long signal bursts.

This OOB section has been moved to the existing G3 window following the G2 

window rather than having “G2 supporting SSC” in the G3 slot. After this 
G3 window, the final speed negotiation window is entered at the highest 

common feature set enabled.

One suggestion was to make the intervals a binary code with a table to 

decode what it means.

Present method uses the particular time area as positive indication of 

support if active signal.

The intervals may need to include an idle time if the squelch detector is 

used, as a discharge time may be required to accurately detect the 

presence of signal.

Failure of the final speed negotiation window shall be handled by a 

higher-level layer (not the PHY).

If there was a failure at the highest negotiated speed and the 

initiator/expander changed the supported options, then how would it reset 

to full capability if the device was changed? 

A concern was raised that using the scrambler in the training sequence may 

involve the link layer.

Since the last interval in the configuration window is idle, the training 

data may start at the beginning of the final speed negotiation window, but 

shall start by the end of a defined RCDT (not necessarily the same length 

of time as the previous RCDT’s). Input is needed on how long this RCDT 

should be.

How is the final speed negotiation window completed? Should there be 

ALIGN0/ALIGN1 after TRAINdone is exchanged to verify dword sync?

Reference documents:

SAS-2 Start-up training sequence (05-397) [Newman]

http://www.t10.org/ftp/t10/document.05/05-397r5.pdf

Proposal New Speed Negotiation for SAS-2 (06-354) [Finch]

http://www.t10.org/ftp/t10/document.06/06-354r0.pdf

Alvin Cox

Seagate Technology, LLC

Tel 405-350-7424

Cell 405-206-4809

E-Mail	alvin.cox at seagate.com




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