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

Lana Chan lana at cadence.com
Wed May 15 15:33:53 PDT 2019

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

  1.  Per Figure K.18: Why does Expander phy (Y) not have "Arbitrating Normal confirmation" from ECM ?  Expander phy[X] has "Arbitrating Normal confirmation"
  2.  If we assume Expander Phy [X] and Expander Phy [Y] has the following state transitions:

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

Our understanding is that if Phy[X] XL state machine is in XL3 and gives Phy Status (Partial Pathway) response to the ECM, the result is "b) Arbitrating (Wait on Partial)" confirmation for Phy[Y] XL1 state machine.  However per Section 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).

then Xl1 to XL5 state transition will never occur.  This also means that back-off reverse/retry will not occur (in XL6 state) for higher priority open address frames received from the expander Phy[Y].  Is our understanding correct?

Similarly (referencing Question (1)), if Expander phy[Y] XL state machine does have  "a) Arbitrating (Normal)" confirmation from ECM this would also block XL1 to XL5 state transition of Phy[Y]. Is this a valid interpretation?

Assuming our interpretation is valid, can we suggest the following instead:
If Request path source address argument and forward open indication destination sas address argument has same address/argument, then XL1 to XL5 state transition should not have condition a) to d) to check

Thank you in advance

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