|L1 (Sleep)||L2 (Suspend)|
|Entry||Explicitly entered via LPM extended transaction||Implicitly entered via 3ms of link inactivity|
|Exit||Device or host-initiated via resume signaling;Remote-wake can be (optionally) enabled/disabled via the LPM transaction.||Device- or host-initiated via resume signaling;Device-initiated resumes can be (optionally) enabled/disabled by software|
|Latencies||Entry: ~10usExit: ~70 us to 1ms (host-specific)||Entry: ~3msExit: >0ms (OS-dependent)|
|Device Power Consumption||Device power consumption level is application and implementation specific||Device power consumption is limited to: ≤500 uA or ≤2.5mA|
Please note that the first token packet is a standard token packet with its newly defined EXT PID. The second token is the extended token packet with a SubPID that is specific to the LPM extension. When its value is LPM, then the 11-bit content would contain definitions that are related to the LPM. In that content definition, it would further describe link states, resume capability and timing duration.
When a host is ready to transition a port from L0 to L1 state, it issues a port command that will result in an LPM transaction being initiated on the affected port. The attached device of the port would send ACK if it is ready to make such a transition or a NYET handshake if it is currently not able to do so. The device must send a STALL if it does not support the requested link state. If the device detects errors or it does not understand the protocol extension transaction, then it sends no handshake.