we are a SAS Core Design team, about SAS protocol, we have some questions, can you help us?
benber.ning at hisilicon.com
Fri Feb 14 18:30:55 PST 2014
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we are a SAS Core Design team, about SAS protocol, we have some questions,
can you help us?
Thanks a lot.
The question is descripted as following
Question1:Can you explain the highlighted text of SAS specification.
When target outstanding send two data frame who belong to the same read10
cmd,initiator response NAK for the first data frame,we donÂ¡Â¯t know whether
target need to wait the second data frameÂ¡Â¯s ACK/NAK(ACK/NAK
balanced),before retransmitting the second data frame.
Because of initiator will response ACK or NAK one by one.When target send
read data frame outstanding,we thought that target should decide to
retransmit d0 or not after receiving all outstanding data framesÂ¡Â¯
ACK/NAK,otherwise target received ACK/NAK will exceed and couldnÂ¡Â¯t get
balanced.We donÂ¡Â¯t know whether we are right.
If target donÂ¡Â¯t need to wait ACK/NAK balanced,can you tell us how the
initiator process the second data frame.
For example,one read10 command have two data frame d0 and d1.
The scenario is described as the followed figures,the relationship of the
DATA frame and ACK/NAK we thought is the blue arrow. The red arrow
stand for that arrows poit to frame must be send after received the
response(ACK/NAK) ate the start of the arrow.The d0(r) stand for retransmit
d0 data frame.
Can you help us to point outthis figure is right or wrong?
Target send d0 and d1 outstanding .While target received the first NAK,we
thought it belong to the d0,and retransmit d0(r) and d1(r)
Question2:received the second NAK target should think it belong to d1 or
Question3:while d0Â¡Â¯s response is NAK,whether initiator could donÂ¡Â¯t
response NAK/ACK for d1?
Question4:while retransmit d1,whether need to wait until receiving d0(r)Â¡Â¯s
Question5:when received the first NAK which belong to d0,target will
retransmit d0 and d1.If received the second response is NAK,which belong to
d1,whether need to retransmit d0 and d1 again?
While received the third NAK/ACK,target should think it belong the d0(r),and
retransmit d0 and d1.
Question6:Before sending d1(r),whether need to wait receiving d0(r)Â¡Â¯s
Question7:Before retransmit d1(r),target received d0(r)Â¡Â¯s NAK,target
should retransmit d0 stand for d1?
Question8:If target received d0(r)Â¡Â¯s response is ACK,d1(r)Â¡Â¯s response
is NAK, target should retransmit d1 only?
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