SAS SP (phy layer) state machine

Jim.Coomes at Jim.Coomes at
Mon Mar 31 13:21:10 PST 2003

* From the T10 Reflector (t10 at, posted by:
* Jim.Coomes at
A problem was introduced to speed negotiation when sas-r03e incorporated
use of the DWS function into the SP (phy layer) state machine SAS speed
negotiation states.

The following transitions: Transition SP10:SAS_AwaitALIGN to SP0:OOB_COMINIT Transition SP11:SAS_AwaitALIGN1 to SP0:OOB_COMINIT Transition SP12:SAS_AwaitSNW to SP0:OOB_COMINIT Transition SP13:SAS_Pass to SP0:OOB_COMINIT

are taken when:

This transition shall occur after receiving a DWS Lost message.

The DWS Lost condition may occur normally during speed negotiation. As the
attached phy's transmitter goes to idle (turns off) the local receiver may
detect invalid words and result in the DWS state machine generating DWS
Lost to the SP state machine. The wording above requires a restart of Link
Reset. This could prevent successful completion of speed negotiation.

The following change is proposed after discussion with Rob:

The following wording from the SP15: SAS_PHY_Ready state should be included
in SP10, SP11, SP12 and SP13 states:

Each time this state receives a DWS Lost message, this state may send a
Start DWS message to the
SP_DWS state machine if it wants to attempt to re-acquire dword
synchronization without running a new link
reset sequence.

The above transitions should be made:

This transition shall occur after receiving a DWS Lost message, if this
state does not send a Start DWS message in response.

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