[T10] [SAS] Query regarding XL1 to XL5 state transition

Lana Chan lana at cadence.com
Thu Mar 14 15:02:44 PDT 2019

Can you please clarify the following questions with respect to the XL state machine  - XL1 to XL5 state transition:

Question 1) Why Expander phy [Y] in XL1 state, doesn't have "Arbitrating Normal confirmation" from ECM ? (As shown in below specification figure K.18)

[cid:image002.jpg at 01D4DA76.EF6385A0]

Question 2) It is fairly possible that, Expander Phy [X] and Expander Phy [Y] is having below condition as state machine

Expander phy [X]

Expander phy [Y] -

having higher priority Add frame received

XL0: Idle

XL0: Idle

XL0: Idle -> XL1:Request_Path

XL0: Idle

XL1:Request_Path to XL2:Request_Open

XL0: Idle

XL2:Request_Open to XL3:Open_Confirm_Wait

XL0: Idle -> XL1:Request_Path

  *   As mentioned in above table, Phy[X] is in XL3 state and Phy[Y] is in XL1 state.
  *   For Phy[Y] XL state machine progress from XL1 to XL5 below condition mentioned Transition XL1:Request_Path to XL5:Forward_Open

This transition shall occur if a Forward Open indication is received and none of the following confirmations have been received:
a) Arbitrating (Normal);
b) Arbitrating (Waiting On Partial);
c) Arbitrating (Blocked On Partial);
d) Arbitrating (Waiting On Connection);
e) Arb Won;
f) Arb Lost;
g) Arb Reject (No Destination);
h) Arb Reject (Bad Destination);
i) Arb Reject (Connection Rate Not Supported);
j) Arb Reject (Zone Violation);
k) Arb Reject (Pathway Blocked); or
l) Arb Reject (Retry).

  *   As mentioned, due to Phy[X] XL state machine is in XL3, it is giving Phy Status (Partial Pathway) response to the ECM and this result in b) Arbitrating (Waiting On Partial) confirmation for Phy[Y] XL1 state machine.
  *   Due to this, XL1 to XL5 state transition never happen ! ; and backoff reverse/retry never happen (in XL6 state) for higher priority open address frame received at expander Phy[Y]
  *   Even as asked in Question 1), if PHY[Y] XL state machine may face  a) Arbitrating (Normal) confirmation from ECM due to PHY[X] situation. It is also blocking situation for XL1 to XL5 state transition of Phy[Y].


  *   If Request path source address argument and forward open indication destination sas address argument has same address/argument, then XL1 to XL5 state trasition should not have condition a) to d) to check

Thank you in advance

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