Gap count analysis for the P1394a BUS

• US 20080263247A1
• Filed: 12/10/2007
• Published: 10/23/2008
• Est. Priority Date: 12/29/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hauck, Jerrold Von
• Granted Patent: US 7,734,855 B2
• Time in Patent Office: Days
• US Class Current: 710/118
• CPC Class Codes: H04L 12/40058 Isochronous transmission
• CPC Class Codes: H04L 12/40084 Bus arbitration
• CPC Class Codes: H04L 43/0858 One way delays
• CPC Class Codes: H04L 43/0864 Round trip delays
• CPC Class Codes: H04L 43/087 Jitter
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route

Abstract

A method of optimizing communication over a high-speed serial bus by minimizing the delay between packets transmitted over the bus is disclosed. The method comprises: calculating the round trip delay between PHYs connected on the bus by pinging; a bus manager sending a configuration packet to all PHYs connected on the bus, the configuration packet containing a minimum gap_count parameter value; and all PHYs connected on the bus sending packets over the bus using the minimum gap_count parameter value as a delay between packets.

Claims

1. (canceled)

2. An apparatus for calculating and enforcing a substantially optimized gap count parameter, said apparatus comprising:

a first module adapted to receive first data, the first data indicating the largest idle period allowable during a first interval;

a second module adapted to receive second data, the second data, indicating the largest period allowable for a second interval; and

a third module adapted to calculate a gap parameter based at least in part upon the largest idle period allowable during the first interval, and the largest period allowable for the second interval.

3. The apparatus of claim 2, wherein the first interval comprises a subaction.

4. The apparatus of claim 2, wherein the first interval comprises an isochronous interval.

5. The apparatus of claim 2, wherein the second interval comprises a subaction gap.

6. The apparatus of claim 2, wherein the third module is further adapted to calculate a gap parameter by a process comprising setting a value such that said value exceeds the largest idle period allowable during the first interval.

7. The apparatus of claim 6, wherein the value comprises a subaction gap timeout.

8. The apparatus of claim 2, wherein the third module is further adapted to calculate a gap parameter by a process comprising setting a value such that said value exceeds the largest period allowable for the second interval.

9. The apparatus of claim 8, wherein the value comprises an arbitration reset gap.

10. The apparatus of claim 2, further comprising:

a fourth module adapted to ensure that a first idle period observed is repeated with a period not less than the largest idle period allowable during the first interval; and

a fifth module adapted to ensure that a second idle period observed is repeated with a period not less than the largest period allowable for the second interval.

11. A storage apparatus comprising a computer readable medium, the medium comprising a program having a plurality of instructions which, when executed by a computer, enforces a gap count parameter by:

setting a first value to be greater than the largest idle period allowable during a first interval;

setting a second value to be greater than the largest period allowable for a second interval;

requiring that a first idle period observed is repeated with a period not less than the largest idle period allowable during the first interval; and

requiring that a second idle period observed is repeated with a period not less than the largest period allowable for the second interval.

12. The storage apparatus of claim 11, wherein the first interval comprises a subaction.

13. The storage apparatus of claim 11, wherein the first interval comprises an isochronous interval.

14. The storage apparatus of claim 11, wherein the second interval comprises a subaction gap.

15. The storage apparatus of claim 11, wherein the first value comprises a subaction gap timeout.

16. The storage apparatus of claim 11, wherein the second value comprises an arbitration reset timeout.

17. A method for enforcing a gap count parameter for use in a data bus, said method comprising:

receiving first data, the first data indicating the largest idle period allowable during a first interval;

receiving second data, the second data indicating the largest period allowable for a second interval;

determining a gap count parameter based at least in part by setting a value greater than at least one of the first and second data.

18. The method of claim 17, wherein the bus comprises a serial bus, and the first interval comprises at least one of a subaction and an isochronous interval.

19. The method of claim 17, wherein the bus comprises a serial bus, and the second interval comprises a subaction gap.

20. The method of claim 17, further comprising:

requiring that a first idle period observed is repeated with a period not less than the largest idle period allowable during the first interval.

21. The method of claim 17, further comprising:

requiring that a second idle period observed is repeated with a period not less than the largest period allowable for the second interval.

22. An apparatus for enforcing a substantially optimized gap count parameter associated with a data bus, said apparatus comprising:

a first module adapted to store a first variable greater than the largest idle period allowable during a first interval;

a second module adapted to store a second variable greater than the largest period allowable for a second interval;

a third module adapted to calculate a substantially optimal gap count parameter based at least in part upon said first and second variables; and

a fourth module adapted to ensure that an idle period observed is not repeated with a period less than at least one of said first and second variables.

23. The apparatus of claim 22, wherein the data bus comprises a serial bus, and the first interval comprises at least one of a subaction and an isochronous interval.

24. The apparatus of claim 22, wherein the second interval comprises a subaction gap.

25. The apparatus of claim 22, wherein the first variable comprises a subaction gap timeout value.

26. The apparatus of claim 22, wherein the second variable comprises an arbitration reset timeout value.

27. The apparatus of claim 22, wherein the third module is further adapted to calculate a substantially optimal gap count parameter based at least in part upon a maximum round trip delay between a first PHY associated with a first node and a second PHY associated with a second node.

28. A method for enforcing a substantially optimized gap count parameter associated with a data bus, said method comprising:

determining the largest idle period allowable during a first interval;

determining the largest period allowable for a second interval; and

deriving a gap count parameter based at least in part by setting a first value to be greater than the largest idle period allowable during the first interval, and based at least in part by setting a second value to be greater than the largest period allowable for the second interval.

29. The method of claim 28, further comprising:

requiring that an idle period observed is not repeated with a period less than at least one of the largest idle period allowable during the first interval, and the largest period allowable for the second interval.

30. The method of claim 28, wherein said deriving a gap count parameter is also based at least in part by calculating a maximum round trip delay between a first PHY associated with a first node and a second PHY associated with a second node.