Message

Per the latest 6Gb SNW-3 proposal pasted below, the TRAIN Completed message is not defined in the document. Based on my read of other parts, I think this should be "TRAIN Transmitted message" as the requirement per 6.7.4.2.3.3 is to send at least 1 TRAIN pattern and after achieving receiver sync, then transition to sending TRAIN_DONE.

6.8.4.12.4 Transition SP29:SAS_Train to SP30:SAS_TrainingDone

This transition shall occur if:

a) this state receives a TRAIN Completed message before the TLT timer expires; and

b) dword synchronization is acquired.

Second point - becuase one end device may be capable of acheiving rx sync faster than the other, it is possible (as seen by our modeling) for the slower device to be in SP29 and before that device gains sync the faster device starts sending TRAIN_DONE.

So it can not be a condition of SP29 -> SP30 to receive a TRAIN pattern, but rather either TRAIN or a TRAIN_DONE pattern This is implied by aquiring receiver synchronization.. Currently, as it is undefined, some people may consider the TRAIN Completed message to be TRAIN Received messsage.

I think it should be further clarified, as I beleive was the original intention, that both TRAIN and TRAIN_DONE serve to allow a receiver to gain synchronization. If true, then the slow device will transition from SP29 to SP30 when gaining rx sync even though it is receiving TRAIN_DONE and not TRAIN.