Dynamically modulating link width

• US 20060034295A1
• Filed: 05/21/2004
• Published: 02/16/2006
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wilcox, Jeffrey R., Schoenborn, Theodore Z., Frodsham, Tim, Cherukuri, Naveen, Spink, Aaron T., Dunning, David, Mannava, Phanindra, Dabral, Sanjay
• Granted Patent: US 8,046,488 B2
• Time in Patent Office: Days
• US Class Current: 370/395.520
• CPC Class Codes: G06F 13/4265 on a point to point bus G06F13/4247, G06F13/4282 take precedence
• CPC Class Codes: H04L 65/60 Network streaming of media packets
• CPC Class Codes: H04L 67/141 Setup of application sessions admission control or resource allocation in data switching networks H04L47/70
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Systems and methods of managing a link provide for receiving a remote width capability during a link initialization, the remote width capability corresponding to a remote port. A link between a local port and the remote port is operated at a plurality of link widths in accordance with the remote width capability.

Claims

1. A method comprising:

receiving a remote width capability during a link initialization, the remote width capability corresponding to a remote port; and

operating a link between a local port and the remote port at a plurality of link widths in accordance with the remote width capability.

2. The method of claim 1, wherein operating the link includes:

establishing a first link width for the link based on the remote width capability and a local width capability;

selecting a second link width based on the remote width capability and an operating condition of the local port; and

modulating the link to the second link width.

3. The method of claim 2, wherein the selecting includes selecting the second link width to be narrower than the first link width, the operating condition including a power saving condition.

4. The method of claim 3 further including placing a portion of the local port in a low power state after modulating the link to the second link width.

5. The method of claim 2, wherein the selecting includes selecting the second link width to be wider than the first link width, the operating condition including an increased bandwidth condition.

6. The method of claim 5, further including bringing a portion of the local port out of a low power state before modulating the link to the second link width.

7. The method of claim 2, further including transmitting data to the remote port at the second link width if a predetermined amount of time has elapsed after the remote port has been notified of the second link width, the predetermined amount of time including a first period and a second period, the first period corresponding to an amount of time required for a link layer of the remote port to relay the second link width to a physical layer of the remote port, the second period corresponding to an amount of time required for the physical layer of the remote port to complete multiplexer switching in support of the second link width.

8. The method of claim 7, further including reading the first period and the second period from a power management register of the local port.

9. The method of claim 8, wherein reading the first period and the second period includes reading a static first period value and a static second period value from the power management register.

10. The method of claim 8, wherein reading the first period and the second period includes reading a dynamic first period value and a dynamic second period value from the power management register.

11. The method of claim 2, further including:

receiving a retry request from the remote port, the retry request indicating that a message associated with the modulating contained errors, the retry request including a current link width of the remote port;

selecting the current link width of the remote port for the local port; and

repeating the modulating.

12. The method of claim 2, further including:

detecting an empty transaction queue associated with an active portion of the local port; and

placing the active portion in an intermediate power state, the intermediate power state having a relatively short reactivation latency.

13. The method of claim 1, wherein receiving the remote width capability includes receiving one or more supported link widths and corresponding lane identifiers.

14. The method of claim 1, wherein operating the link includes operating a unidirectional link at the plurality of link widths.

15. An apparatus comprising:

a local port having control logic to receive a remote width capability during a link initialization, the remote width capability to correspond to a remote port, and operate a link between the local port and the remote port at a plurality of link widths in accordance with the remote width capability.

16. The apparatus of claim 15, wherein the control logic is to establish a first link width for the link based on the remote width capability and a local width capability, select a second link width based on the remote width capability and an operating condition of the local port and modulate the link to the second link width.

17. The apparatus of claim 16, wherein the second link width is to be narrower than the first link width, the operating condition to include a power saving condition, the control logic to place a portion of the local port in a low power state after modulating the link to the second link width.

18. The apparatus of claim 16, wherein the second link width is to be wider than the first link width, the operating condition to include an increased bandwidth condition, the control logic to bring a portion of the local port out of a low power state before modulating the link to the second link width.

19. The apparatus of claim 16, wherein the control logic is to transmit data to the remote port at the second link width if a predetermined amount of time has elapsed after the remote port has been notified of the second link width, the predetermined amount of time to include a first period and a second period, the first period to correspond to an amount of time required for a link layer of the remote port to relay the second link width to a physical layer of the remote port, the second period to correspond to an amount of time required for the physical layer of the remote port to complete multiplexer switching in support of the second link width.

20. The apparatus of claim 16, wherein the control logic is to detect an empty transaction queue associated with an active portion of the local port and place the active portion in an intermediate power state, the intermediate power state to have a relatively short reactivation latency.

21. The apparatus of claim 15, wherein the remote width capability is to include one or more supported link widths and corresponding lane identifiers.

22. The apparatus of claim 15, wherein the link is to include a unidirectional link.

23. A system comprising:

a remote port;

a unidirectional link coupled to the remote port; and

a local port coupled to the link, the local port including control logic to receive a remote width capability from the remote port during a link initialization, and operate the link at a plurality of link widths in accordance with the remote width capability.

24. The system of claim 23, wherein the control logic is to establish a first link width for the link based on the remote width capability and a local width capability, select a second width based on the remote width capability and an operating condition of the local port and modulate the link to the second link width.

25. The system of claim 24, wherein the second link width is to be narrower than the first link width, the operating condition to include a power saving condition, the control logic to place a portion of the local port in a low power state after modulating the link to the second link width.

26. The system of claim 25, wherein the remote port includes control logic to receive notification of the second link width from the local port and place a portion of the remote port in a low power state.

27. The system of claim 24, wherein the second link width is to be wider than the first link width, the operating condition to include an increased bandwidth condition, the control logic to bring a portion of the local port out of a low power state before modulating the link to the second link width.

28. The system of claim 27, wherein the remote port includes control logic to receive notification of the second link width from the local port and bring a portion of the remote port out of a low power state.

29. The system of claim 24, wherein the control logic is to detect an empty transaction queue associated with an active portion of the local port and place the active portion in an intermediate power state, the intermediate power state to have a relatively short reactivation latency.

30. The system of claim 23, wherein the link is part of a point-to-point network interconnect having a layered communication protocol.

34. The method of claim 27, further including transmitting data to the remote port at the second link width if a predetermined amount of time has elapsed after the remote port has been notified of the second link width, the predetermined amount of time including a first period and a second period, the first period corresponding to an amount of time required for a link layer of the remote port to relay the second link width to a physical layer of the remote port, the second period corresponding to an amount of time required for the physical layer of the remote port to complete multiplexer switching in support of the second link width.

31. A method comprising:

receiving a remote width capability during a link initialization between a local port and a remote port, the remote width capability corresponding to the remote port and including one or more supported link widths and corresponding lane identifiers;

establishing a first link width for a link based on the remote width capability and a local width capability;

selecting a second link width based on the remote width capability and an operating condition of the local port;

modulating the link to the second link width;

detecting an empty transaction queue associated with an active portion of the local port; and

placing the active portion in an intermediate power state, the intermediate power state having a relatively short reactivation latency.

32. The method of claim 31, wherein the selecting includes selecting the second link width to be narrower than the first link width, the operating condition including a power saving condition, the method further including placing a portion of the local port in a low power state after modulating the link to the second link width, the low power state having a relatively long reactivation latency.

33. The method of claim 31, wherein the selecting includes selecting the second link width to be wider than the first link width, the operating condition including an increased bandwidth condition, the method further including bringing a portion of the local port out of a low power state before modulating the link to the second link width, the low power state having a relatively long reactivation latency.