Link Wakeup from L2 Low Power State

When a device's Link is in the L2 low power state, its main power is turned off though Vaux is still applied. A device returns to the full-on L0 power state by one of two methods. Either the device signals a wakeup event or Power Management software triggers the wakeup procedure “Waking Non-Communicating Links” on page 642.

Device Signals Wakeup

The powered down device (device(s) are in D3Cold with Vaux valid) whose Link is in L2 state, is able to signal a wakeup event either through signaling a Beacon (see “Beacon Signaling” on page 469) upstream towards the root complex or by asserting WAKE#. The wakeup event ultimately results in the power controller re-applying power and clock to the device (or group of ...

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