Slot Status Register Implementation

A downstream port with hot-plug capabilities supports these hot-plug events:

  • Slot events:
    • Attention Button Pressed – Indicated by the ATTENTION_BUTTON_N input.
    • Power Fault Detected – Indicated by the POWER_FAULT_N input.
    • MRL Sensor Changed – Indicated by the MRL_SENSOR_N Input. A change in this input is detected by the Controller and captured in status register.
    • Presence Detect Changed – Indicated by the PRSNT_N input. A change in this input is detected by the Controller and captured in status register.
  • Command Completed Events, Indicated by COMMAND_COMPLETED input.
  • Data Link Layer State Changed Events, Indicated by "Link Status Register" DLL Active Bit.

Each of these events has a status field, which indicates that an event has occurred but has not yet been processed by software, and an enable field, which indicates whether the event is enabled for software notification. Some events also have a capability field, which indicates whether the event type is supported on the Port.