[T10] 答复: Questoin about SAS SSC

Guojian (F) guojian111 at hisilicon.com
Tue Oct 27 18:14:18 PDT 2015

Thanks Harvey!  It is very nice of you.


发件人: Harvey Newman [mailto:harvey.newman at avagotech.com]
发送时间: 2015年10月23日 22:34
收件人: Guojian (F)
抄送: t10 at t10.org
主题: Re: [T10] Questoin about SAS SSC

Hi Jason,

Your general understanding is correct.  The phy capabilities TX SSC TYPE bit indicates the SSC type (i.e., center-spreading or down-spreading).  This allowed a product that is connected to optimize the Rx to receive SSC if they desire. The term "may" indicates it "may or may not" without any preference. The optimization is optional. If the configuration bits also indicate operation "with SSC" the requirement is the receiver be compliant even in the presence of the full SSC deviation advertised by the TX SSC TYPE bit.   The rules for initiator center-spread and target down-spread are specified elsewhere in the standard and this is the expected operation.

In the wording of your question, "Is that mean RX should ensure..." you have used the term should, where in this case in spec language this is a shall. The term should indicates a flexibility of choice but once you indicate support for SSC it is a requirement to be fully compliant in the presence of SSC.  It is the optimization that is optional.

Harvey Newman
Avago Technologies

On Thu, Oct 22, 2015 at 11:19 PM, Guojian (F) <guojian111 at hisilicon.com<mailto:guojian111 at hisilicon.com>> wrote:
  I have a question about SAS SSC.
  From the attached Picture, we can see that initiator and target would notify each other TX SSC TYPE by transmitting SNW-3 phy capabilities.
  NOTE 13 - The phy’s receiver may use the TX SSC TYPE bit to optimize its clock data recovery circuitry (seeSAS-3).
  Is that means RX should ensure it can receive center-spreading SSC or down-spreading SSC signal by using received TX SSC TYPE?

  So, it is possible that initiator transmit center-spreading SSC signal and target transmit down-spreading SSC signal. Is that right?

Thanks and Best Regards!

Jason Guo
[cid:image001.png at 01D110A2.EE10F490]

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Harvey Newman
Avago Technologies
(408) 433-4028
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