Datasheet

xHCI Controller Registers (D20:F0)
456 Intel® Xeon® Processor D-1500 Product Family
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
13:10 Port Speed (Port_Speed).
A device attached to this port operates at a speed defined by the following codes:
All other values reserved. Please refer to the eXtensible Host Controller Interface for Universal Serial
Bus Specification for additional details.
9 Port Power (PP) — RO. Read-only with a value of 1. This indicates that the port does have power.
Note: This bit is in the Suspend Well.
8:5 Port Link State (PLS) — R/W. This field is used to power manage the port and reflects its current
link state.
When the port is in the Enabled state, system software may set the link U-state by writing this field.
System software may also write this field to force a Disabled to Disconnected state transition of the
port.
Note: The Port Link State Write Strobe (LWS) shall be set to 1b to write this field.
Notes:
1. This field is undefined if PP = 0.
2. Transitions between different states are not reflected until the transition is complete.
3. This bit is in the Suspend Well.
Bit Description
Value Speed
0100 SuperSpeed (5 Gb/s)
Write Value Description
0 The link shall transition to a U0 state from any of the U-states.
2 USB 2.0 ports only. The link should transition to the U2 State.
3 The link shall transition to a U3 state from any of the U-states. This
action selectively suspends the device connected to this port. While the
Port Link State = U3, the hub does not propagate downstream-directed
traffic to this port, but the hub will respond to resume signaling from the
port.
5 USB 3.0 ports only. If the port is in the Disabled state (PLS = Disabled,
PP = 1), then the link shall transition to a RxDetect state and the port
shall transition to the Disconnected state, else ignored.
15 USB 2.0 ports only. If the port is in the U3 state (PLS = U3), then the
link shall remain in the U3 state and the port shall transition to the
U3Exit substate, else ignored.
All other values Ignored
Read Value Definition
0 Link is in the U0 State
1 Link is in the U1 State
2 Link is in the U2 State
3 Link is in the U3 State (Device Suspended)
4 Link is in the Disabled State
5 Link is in the RxDetect State
6 Link is in the Inactive State
7 Link is in the Polling State
8 Link is in the Recovery State
9 Link is in the Hot Reset State
10 Link is in the Compliance Mode State
11 Link is in the Test Mode State
12–14 Reserved
15 Link is in the Resume State