Apparatus and method for dynamically enabling and disabling write XFR — RDY

• US 8,732,357 B2
• Filed: 10/28/2010
• Issued: 05/20/2014
• Est. Priority Date: 10/28/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Klein, Steven Edward, Kalos, Matthew Joseph, Dang, Dung Ngoc, Wayne, Sherman Daniel
• Primary Examiner(s): Huson, Zachary K
• Application Number:
  US12/914,024
• Publication Number:
  US 20120110222A1
• Time in Patent Office: 1,300 Days
• Field of Search: 710/52, 710/57, 710/17
• US Class Current: 710/52
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247

Abstract

A method for dynamically enabling and disabling use of XFR_RDY is disclosed herein. In one embodiment of the invention, such a method includes receiving a write command at a target and determining whether XFR_RDY is enabled or disabled for the write command. In the event XFR_RDY is disabled, the method determines whether one or more buffers are available at the target. If at least one buffer is available, the method processes the write command by writing data associated with the write command to the one or more buffers. The method then returns information indicating the number of buffers that are still available at the target after completing the write command. A corresponding apparatus and computer program product are also disclosed and claimed herein.

Claims

1. A method for dynamically enabling and disabling operation in transfer ready (XFR_RDY) mode, the method comprising:

receiving, from an initiator, a write command at a target, the target comprising a plurality of buffers for processing write commands;

determining whether XFR_RDY is disabled for the write command;

in the event XFR_RDY is disabled, determining whether at least one buffer from the plurality of buffers is available on the target;

in the event at least one buffer is available, processing the write command by writing data associated with the write command to the at least one buffer;

calculating, at the target, a total number of buffers that are still available on the target after processing the write command; and

transmitting the total number to the initiator.

2. The method of claim 1, further comprising, in the event at least one buffer is not available, discarding data associated with the write command at the target.

3. The method of claim 2, wherein discarding data further comprises returning status indicating that the write command failed and should be re-driven with XFR_RDY enabled.

4. The method of claim 1, wherein, prior to transmitting another write command with XFR_RDY disabled to the target, the initiator determines if the total number of buffers still available on the target is greater than a number of outstanding write commands the initiator has with the target.

5. The method of claim 4, wherein the initiator is configured to transmit another write command with XFR_RDY disabled if the initiator determines that the total number of buffers still available on the target is greater than the number of outstanding write commands the initiator has with the target.

6. The method of claim 4, wherein the initiator is configured to transmit a write command with XFR_RDY enabled if the initiator determines that the total number of buffers still available on the target is not greater than the number of outstanding write commands the initiator has with the target.

7. A computer program product to dynamically enable and disable operation in transfer ready (XFR_RDY) mode, the computer program product comprising a non-transitory computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code comprising:

computer-usable program code to receive, from an initiator, a write command at a target, the target comprising a plurality of buffers for processing write commands;

computer-usable program code to determine whether XFR_RDY is disabled for the write command;

computer-usable program code to, in the event XFR_RDY is disabled, determine whether at least one buffer from the plurality of buffers is available on the target;

computer-usable program code to, if at least one buffer is available, process the write command by writing data associated with the write command to the at least one buffer;

computer-usable program code to calculate, at the target, a total number of buffers that are still available on the target after processing the write command; and

computer-usable program code to transmit the total number to the initiator.

8. The computer program product of claim 7, further comprising computer-usable program code to, if at least one buffer is not available, discard data associated with the write command.

9. The computer program product of claim 8, wherein discarding data further comprises returning status indicating that the write command failed and should be re-driven with XFR_RDY enabled.

10. The computer program product of claim 7, further comprising computer-usable program code on the initiator to, prior to transmitting another write command with XFR_RDY disabled to the target, determine if the total number of buffers still available on the target is greater than a number of outstanding write commands with the target.

11. The computer program product of claim 10, further comprising computer-usable program code on the initiator to transmit another write command with XFR_RDY disabled to the target if the total number of buffers still available on the target is greater than the number of outstanding write commands with the target.

12. The computer program product of claim 10, further comprising computer-usable program code on the initiator to transmit a write command with XFR_RDY enabled if the total number of buffers still available on the target is not greater than the number of outstanding write commands with the target.

13. A system to dynamically enable and disable operation in transfer ready (XFR_RDY) mode, the system comprising:

an initiator to transmit a write command;

a target to receive the write command and determine whether XFR_RDY is disabled for the write command, the target comprising a plurality of buffers for processing write commands;

the target further configured to, in the event XFR_RDY is disabled, determine whether at least one buffer from the plurality of buffers is available on the target;

the target further configured to, if at least one buffer is available on the target, process the write command by writing data associated with the write command to the at least one buffer;

the target further configured to calculate a total number of buffers that are still available on the target after processing the write command; and

the target further configured to transmit the total number to the initiator.

14. The system of claim 13, wherein the target is further configured to, if at least one buffer is not available, discard data associated with the write command.

15. The system of claim 14, wherein the target is further configured to, in the event the data is discarded, return status indicating that the write command failed and should be re-driven with XFR_RDY enabled.

16. The system of claim 13, wherein the initiator is further configured to, prior to transmitting another write command with XFR_RDY disabled to the target, determine if the total number of buffers still available on the target is greater than a number of outstanding write commands with the target.

17. The system of claim 16, wherein the initiator is further configured to transmit another write command with XFR_RDY disabled to the target if the total number of buffers still available on the target is greater than the number of outstanding write commands with the target.

18. The system of claim 16, wherein the initiator is further configured to transmit a write command with XFR_RDY enabled if the total number of buffers still available on the target is not greater than the number of outstanding write commands with the target.

19. A method for dynamically enabling and disabling operation in transfer ready (XFR_RDY) mode, the method comprising:

receiving, at an initiator, information indicating the total number of buffers that are available on a target, the target comprising a plurality of buffers for processing write commands;

determining, at the initiator, if the total number of buffers still available on the target is greater than a number of outstanding write commands the initiator has with the target;

transmitting, by the initiator, a write command with XFR_RDY disabled if the total number of buffers available on the target is greater than the number of outstanding write commands the initiator has with the target; and

transmitting, by the initiator, a write command with XFR_RDY enabled if the total number of buffers available on the target is not greater than the number of outstanding write commands the initiator has with the target.

20. The method of claim 19, further comprising re-driving, by the initiator, the write command with XFR_RDY enabled in the event the write command with XFR_RDY disabled fails.