Author Topic: USB SS Low power exit  (Read 10783 times)


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USB SS Low power exit
« on: August 19, 2010, 08:21:42 am »
If we have a Link partner initiating wakeup too early such that the other link partner has not enabled its Receiver to receive LFPS exit signalling, then how do we make sure that the exit signalling process successfully completes.

LP1 (LTSSM state U1/2) -->
                               < -- LP2 (LTSSM state U0)
LP1( LFPS exit signals) -->
                               < -- LP2 (LTSSM state U1)
                               < -- LP2( Ping, as it never detected LFPS start)
LP1( Successful exit) ( as LFPS as small as ping can also be enough for Host to move ahead with successful U1/2 exit)
LP1 ( -->
                             <-- LP2 ( waits for LFPS exit)
How to avoid a condition