Performance optimization of data transfer for soft information generation

• US 9,367,246 B2
• Filed: 08/09/2013
• Issued: 06/14/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Frayer, Jack Edward, Olbrich, Aaron K.
• Primary Examiner(s): Tsai, Henry
• Assistant Examiner(s): Phan, Dean
• Application Number:
  US13/963,444
• Publication Number:
  US 20140281044A1
• Time in Patent Office: 1,040 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1048 using arrangements adapted for a specific error detection or correction feature
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/068 Hybrid storage device
• CPC Class Codes: H03M 13/3723 using means or methods for the initialisation of the decoder
• CPC Class Codes: H03M 13/3769 using symbol combining, e.g. Chase combining of symbols received twice or more
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence

Abstract

A single command initiates a first read operation and sequence of one or more additional read operations from the same portion of memory. The one or more additional read operations are terminable after the first read operation provides a first plurality of data values that is made available to a requesting device and/or module. In some implementations, the first plurality of data values includes hard information values. Subsequent pluralities of data values are generated from the same portion of memory until a terminating event occurs. In some implementations, until a terminating event occurs, a respective hybrid plurality of data values is generated by combining the latest read plurality of data values with one of a previously generated hybrid plurality of data values and the first plurality of data values. Each hybrid plurality of data values is representative of a corresponding plurality of soft information values.

Claims

1. A method of reading from a storage medium, the method comprising:

receiving from a requesting device a control command of a first type;

responding to receiving the control command of the first type by;

performing a first read operation, using a first reading signal value, to obtain a first plurality of data values from a portion of the storage medium;

after performing the first read operation, initiating performance of one or more additional read operations, each additional read operation using a respective reading signal value different from the first reading signal value to obtain a subsequent plurality of data values from the same portion of the storage medium as the first read operation;

in response to receiving a subsequent control command from the requesting device prior to completion of a predefined number of the additional read operations, the receipt of the subsequent control command indicating that the first read operation or one of the additional read operations was successful, terminating performance of the one or more additional read operations; and

in response to completion of the predefined number of the additional read operations, terminating performance of the one or more additional read operations.

2. The method of claim 1, wherein the method is performed by circuitry in the storage medium in response to control commands received from a memory controller coupled to the storage medium, and wherein the subsequent control command, from the memory controller, is of a type that causes termination of the one or more additional read operations.

3. The method of claim 1, further comprising:

storing the first plurality of data values in a buffer;

transferring the first plurality of data values from the buffer to the requesting device; and

initiating performance of a first additional read operation of the one or more additional read operations during a time period that overlaps with the transfer of the first plurality of data values from the buffer to the requesting device.

4. The method of claim 1, further comprising:

storing the first plurality of data values in a buffer;

setting a status bit that is configured for reading by the requesting device; and

initiating performance of a first additional read operation of the one or more additional read operations at a time period proximate to a time that the status bit is set.

5. The method of claim 1, wherein so long as performance of the one or more additional read operations has not been terminated, the method includes generating, in response to a completion of each of the one or more additional read operations, a respective hybrid plurality of data values by combining the latest read plurality of data values with one of a previously generated hybrid plurality of data values and the first plurality of data values.

6. The method of claim 1, further comprising:

receiving from a requesting device a control command of a second type, wherein the second type differs from the first type by indicating a request for a single read of a respective portion of the storage medium;

responding to receiving the control command of the second type by;

performing a single read operation to obtain data values from a portion of the storage medium;

storing the obtained data values in a buffer; and

transferring the obtained data values from the buffer to the requesting device.

7. The method of claim 1, wherein the one or more additional read operations is limited to a predefined number of read operations.

8. The method of claim 1, wherein initiating performance of one or more additional read operations occurs in response to a first condition.

9. The method of claim 8, wherein the first condition includes determining that a message, that indicates that the first plurality of data values can be decoded successfully, has not been received within a first duration.

10. The method of claim 8, wherein the first condition includes determining that a message, that indicates that the first plurality of data values has been successfully decoded, has not been received within a first duration.

11. The method of claim 5, further comprising:

storing the first plurality of data values in a buffer; and

transmitting a first message indicating that the first plurality of data values is available to be read from the buffer.

12. The method of claim 11, further comprising:

storing each respective hybrid plurality of data values in the buffer by overwriting any previously generated hybrid plurality of data values stored in the buffer; and

transmitting a subsequent message indicating that a new hybrid plurality of data values is available to be read from the buffer each time a hybrid plurality of data values is newly stored in the buffer.

13. The method of claim 5, wherein generating each respective hybrid plurality of data values includes an exclusive-or (XOR) between each of the latest read of the one or more subsequent pluralities of data values and one of a previously generated hybrid plurality of data values and the first plurality of data values.

14. A device, comprising:

a storage medium; and

control circuitry configured to;

receive from a requesting device a control command of a first type;

respond to receiving the control command of the first type by;

performing a first read operation, using a first reading signal value, to obtain a first plurality of data values from a portion of the storage medium;

after performing the first read operation, initiating performance of one or more additional read operations, each additional read operation using a respective reading signal value different from the first reading signal value to obtain a subsequent plurality of data values from the same portion of the storage medium as the first read operation; and

in accordance with a determination that a subsequent control command has been received from the requesting device prior to completion of a predefined number of the additional read operations, the receipt of the subsequent control command indicating that the first read operation or one of the additional read operations was successful, terminating performance of the one or more additional read operations; and

in accordance with a determination that a subsequent control command has not been received from the requesting device prior to completion of a predefined number of the additional read operations, terminating performance of the one or more additional read operations in accordance with completion of the predefined number of the additional read operations.

15. The device of claim 14, wherein the requesting device is a memory controller coupled to the storage medium, and the subsequent control command, from the memory controller, is of a type that causes termination of the one or more additional read operations.

16. The device of claim 15, wherein the control circuitry is further configured to:

store the first plurality of data values in a buffer;

transfer the first plurality of data values from the buffer to the requesting device; and

initiate performance of a first additional read operation of the one or more additional read operations during a time period that overlaps with the transfer of the first plurality of data values from the buffer to the requesting device.

17. The device of claim 14, wherein the control circuitry is further configured to:

store the first plurality of data values in a buffer;

set a status bit that is configured for reading by the requesting device; and

initiate performance of a first additional read operation of the one or more additional read operations at a time period proximate to a time that the status bit is set.

18. The device of claim 14, wherein so long as performance of the one or more additional read operations has not been terminated, the control circuitry generates, in response to a completion of each of the one or more additional read operations, a respective hybrid plurality of data values by combining the latest read plurality of data values with one of a previously generated hybrid plurality of data values and the first plurality of data values.

19. The device of claim 14, wherein the control circuitry is configured to:

receive from the requesting device a control command of a second type, wherein the second type differs from the first type by indicating a request for a single read of a respective portion of the storage medium;

respond to receiving the control command of the second type by;

performing a single read operation to obtain data values from a portion of the storage medium;

storing the obtained data values in a buffer; and

transferring the obtained data values from the buffer to the requesting device.

20. The device of claim 14, wherein the one or more additional read operations is limited to a predefined number of read operations.

21. The device of claim 14, wherein initiating performance of one or more additional read operations occurs in response to a first condition.

22. The device of claim 21, wherein the first condition includes determining that a message, that indicates that the first plurality of data values can be decoded successfully, has not been received within a first duration.

23. The device of claim 21, wherein the first condition includes determining that a message, that indicates that the first plurality of data values has been successfully decoded, has not been received within a first duration.

24. The device of claim 18, wherein the control circuitry is further configured to:

store the first plurality of data values in a buffer; and

transmit a first message indicating that the first plurality of data values is available to be read from the buffer.

25. The device of claim 24, wherein the control circuitry is further configured to:

store each respective hybrid plurality of data values in the buffer by overwriting any previously generated hybrid plurality of data values stored in the buffer; and

transmit a subsequent message indicating that a new hybrid plurality of data values is available to be read from the buffer each time a hybrid plurality of data values is newly stored in the buffer.

26. The device of claim 18, wherein generating each respective hybrid plurality of data values includes an exclusive-or (XOR) between each of the latest read of the one or more subsequent pluralities of data values and one of a previously generated hybrid plurality of data values and the first plurality of data values.

27. A method of reading from a storage medium, the method comprising:

receiving from a requesting device a control command of a first type;

responding to receiving the control command of the first type by;

performing a first read operation, using a first reading signal value, to obtain a first plurality of data values from a portion of the storage medium;

after performing the first read operation, initiating performance of one or more additional read operations, each additional read operation using a respective reading signal value different from the first reading signal value to obtain a subsequent plurality of data values from the same portion of the storage medium as the first read operation;

in accordance with a determination that a subsequent control command has been received from the requesting device prior to completion of a predefined number of the additional read operations, the receipt of the subsequent control command indicating that the first read operation or one of the additional read operations was successful, terminating performance of the one or more additional read operations; and

in accordance with a determination that a subsequent control command has not been received from the requesting device prior to completion of a predefined number of the additional read operations, terminating performance of the one or more additional read operations in accordance with completion of the predefined number of the additional read operations.

28. The method of claim 27, wherein the method is performed by circuitry in the storage medium in response to control commands received from a memory controller coupled to the storage medium, and wherein the subsequent control command, from the memory controller, is of a type that causes termination of the one or more additional read operations.