Method and apparatus for border node behavior on a full-duplex bus

• US 20070067523A1
• Filed: 11/16/2006
• Published: 03/22/2007
• Est. Priority Date: 01/18/2000
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Whitby-Strevens, Colin, Hauck, Jerrold
• Granted Patent: US 7,490,174 B2
• Time in Patent Office: Days
• US Class Current: 710/105
• CPC Class Codes: H04L 12/40052 High-speed IEEE 1394 serial bus bus transfer protocol on a daisy chain bus using an embedded synchronisation G06F13/426
• CPC Class Codes: H04L 12/40058 Isochronous transmission
• CPC Class Codes: H04L 12/40071 Packet processing; Packet format adaptation of digital video signals for transport over a specific network H04N21/2381, H04N21/4363, H04N21/4381; packet switches H04L49/00; intermediate storage or scheduling H04L49/90
• CPC Class Codes: H04L 12/6418 Hybrid transport

Abstract

A method and apparatus relating to the behavior of border nodes within a high performance serial bus system is disclosed. A method for determining and communicating the existence of a hybrid bus is disclosed. A method for determining a path to a senior border node is disclosed, as is a method for identifying a senior border node Various methods for properly issuing gap tokens within a beta cloud are disclosed.

Claims

1-3. -3. (canceled)

4. In a communications system comprising at least one serial bus, at least one node operating in a first mode, and at least one other node operating in a second mode, a border apparatus comprising:

a first port operatively coupled to said at least one node operating in said first mode;

a second port operatively coupled to said at least one node operating in said second mode; and

a transfer apparatus adapted to transfer gap timing requirements associated with said at least one node operating in said second mode to said border apparatus.

5. The border apparatus of claim 4, wherein said border apparatus operates according to a hybrid bus communication protocol.

6. The border apparatus of claim 5, wherein said system comprises a full-duplex communications system.

7. The border apparatus of claim 5, wherein said first mode comprises a legacy mode, and said second mode comprises a mode which is accelerated relative to said legacy mode.

8. The border apparatus of claim 5, wherein said hybrid bus communication protocol comprises regulating an idle duration of said at least one other node operating in said second mode.

9. The border apparatus of claim 8, wherein said hybrid bus communication protocol further comprises:

detecting a first idle duration which is related to a subaction gap, and issuing an asynchronous start signal in response thereto; and

detecting a second idle duration which is related to an arbitration reset gap, and issuing an arbitration reset signal in response thereto.

10. The border apparatus of claim 5, wherein said hybrid bus communication protocol is further adapted to enforce proper arbitration between said border apparatus and said at least one node operating in said second mode, even if said at least one node operating in said first mode comprises a parent of said border apparatus.

11. The border apparatus of claim 7, wherein said legacy mode comprises a mode compliant with IEEE Std. 1394a, and said accelerated mode comprises a mode compliant with IEEE Std. 1394b.

12. In a communications system comprising a serial bus, a method of insuring that control will revert to a device which can act as proxy between a legacy mode cloud and an accelerated mode cloud of a hybrid bus comprising:

granting bus ownership status to a predetermined port by a device responsible for granting arbitration requests; and

in the alternative, passing control of the serial bus towards said device by the device responsible for granting arbitration requests.

13. The method of claim 12, wherein said acts of granting and passing are implemented through at least the use of a plurality of packet-ending signals.

14. The method of claim 13, wherein said plurality of packet-ending signals comprise symbols transmitted on a bus.

15. The method of claim 13, wherein said plurality of packet-ending signals are encoded in logic on a PHY.

16. The method of claim 13, wherein said plurality of packet-ending signals comprise:

a grant packet ending symbol;

a null data packet ending symbol; and

an end-of-data packet ending symbol.

17. The method of claim 16, wherein said act of granting bus ownership status to said predetermined port by said device responsible for granting arbitration further comprises:

determining if there are any in-phase requests at said predetermined port to grant, and if so, issuing said grant packet ending symbol to said predetermined port.

18. The method of claim 17, wherein said act of granting bus ownership status to said predetermined port by said device responsible for arbitration further comprises issuing said null data packet ending symbol to at least one other port.

19. The method of claim 16, wherein said act of passing control further comprises determining whether said device is a senior border node and if so, issuing said end-of-data packet ending symbol out said predetermined port.

20. The method of claim 16, wherein said grant packet ending symbol communicates to a receiving device that the end of a sub-action has been reached and the receiving device comprises the newly designated bus owner.

21. The method of claim 16, wherein said null data packet ending symbol communicates to a receiving device that said serial bus is being actively granted to another PHY.

22. The method of claim 21, wherein said receiving device further comprises an idle timer, and said null data packet communicates to said receiving device not to allow said idle timer to time out.

23. In a serial bus communications system, a senior border device which may act as proxy between a legacy mode cloud and an accelerated mode cloud in a hybrid bus, said senior border device adapted to operate according to the method comprising:

granting bus ownership status to an accelerated mode device via an accelerated mode port;

issuing gap tokens to said accelerated mode cloud; and

reassuming control after said accelerated mode device has finished its respective tasks.

24. The senior border device of claim 23, wherein said buss ownership status comprises BOSS status, and said method further comprises ensuring compliance with one or more gap timers.

25. In a serial bus communications system, a method of assuring that bus control will eventually revert back to a senior border node, comprising:

granting BOSS status to a predetermined port of a Beta device; and

passing control of the serial bus communications system towards said senior border node by the Beta device after said act of granting BOSS status.

26. The method of claim 25, further comprising identifying said senior node according to the method comprising:

determining whether said senior border node was the last node to transmit a self-identification packet; and

marking said senior border node as identified if said senior border node was the last node to transmit the self-identification packet.

27. The method of claim 25, wherein said acts of granting and passing are implemented through the use of at least a plurality of packet-ending symbols.

28. The method of claim 27, wherein said plurality of packet-ending symbols, comprise at least two of:

a grant packet ending symbol;

a null data packet ending symbol; and

a data-end packet ending symbol.

29. The method of claim 28, wherein said act of granting ownership status to said predetermined port by said Beta device further comprises determining if there is any in-phase requests at said predetermined port to grant and if so, issuing a grant packet ending symbol to said predetermined port.

30. The method of claim 29, wherein said act of granting ownership status to said predetermined port by said Beta device further comprises issuing said null data packet ending symbol to at least one other port.

31. A device in communication with a full-duplex communications system having at least one node, the device configured to determine and communicate the existence of a hybrid bus by performing the method comprising:

determining whether a node is a border node;

forwarding isochronous and asynchronous requests as normal if said node is not a border node;

and if said node is a border node, then;

issuing a first request if there are no asynchronous requests to forward;

forwarding said asynchronous request if there are asynchronous requests to forward;

issuing a second request if there are no isochronous requests to forward; and

forwarding said isochronous requests if there are isochronous requests to forward.

32. The device of claim 31, wherein the node comprises a plurality of ports, and wherein determining whether said node is a border node comprises determining that both at least a legacy connection and a IEEE P1394b connection have been made to ports in the plurality.

33. The device of claim 31, wherein the first and second requests comprise Border_low requests forwarded to a BOSS node, wherein each of the Border_low requests if issued is given a priority that allows pipelined in-phase arbitration requests to be handled before the Border_low request is forwarded to the BOSS node.

34. The device of claim 31, wherein the first request comprises a different request from the second request.

35. The device of claim 31, wherein the node comprises a plurality of ports, and determining whether said node is a border node comprises determining that both at least a legacy connection and a IEEE P1394b connection have been made to ports of said plurality of ports.

36. The device of claim 31, wherein at least one of said first and second requests comprises a Border_low request, said Border_low request being forwarded to a BOSS node, wherein the Border_low request comprises a priority that allows pipelined in-phase arbitration requests to be handled before the Border_low request is forwarded to the BOSS node.

37. The device of claim 31, wherein said first and second requests comprise Border_low requests.