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SAS Interface
36 C141-C013
Figure 1.9 describes SAS OOB signal detection by the SP receiver.
1
2
3
4
n
n
1
2
3
4
n
Any transitions
COMINIT
detected
COMRESET/COMINIT
COMINIT
negation
COMSAS
Any transitions
idle
ALIGN burst
nth
idle/Burst pair
idle/Burst pair
COMSAS
detected
COMSAS
negation
Figure 1.9 OOB signal detection
1.3.5 SAS OOB sequency
During the OOB sequence, the INIT and the drive first send the COMINIT signal
to each other, then the COMSAS signal. When they both have received the
COMSAS signal from each other, the OOB sequence is recognized as having been
performed successfully. Depending on the power-on timing, reception of the
COMINIT signal from the other side may not be detected. In such a case,
however, the OOB sequence is recognized as having been performed successfully
if the COMINIT and COMSAS signals have been sent by the time the COMSAS
signal from the other side is received.
When the OOB sequence is successful, the SAS speed negotiation sequence starts.
Figure 1.10 shows several different SAS OOB sequences between phy A and phy
B, with phy A starting the SAS OOB sequence at the same time as phy B, before
phy B, and before phy B powers on.