How to compare read and write delay calibrations to pinpoint memory issue ?

[peteramond]

Hi All,

In the document Freescale i.MX6 DRAM Port Application Guide – DDR3 we can see the sample read and write delay calibrations in section 3.1.2

From following write level calibration of  2 boards we can see from the red highlighted lines Board 1 has got 0x11111111 too early than Board 2. 

1) What can we figure from this ? If 0 represent pass values and 1 represent fail; according to user manual why some results are like 0x10111111 ?

2) If wider the 0 window, it represent more pass results for the ddr. Is that good or bad ?

3) Why it is showing at top and bottom half all 1 ? Is that mean read or write fails ? If at the very bottom result include 0 result what can we say about that byte lane ?

4) Can we get any failures of byte lane of the memory from this results ?

Regards,

Peter.

Board 1 (Working Board)

1. ABS_OFFSET=0x00000000   result[00]=0x11111111
2. ABS_OFFSET=0x04040404   result[01]=0x10111111
3. ABS_OFFSET=0x08080808   result[02]=0x10110111
4. ABS_OFFSET=0x0C0C0C0C   result[03]=0x10110010
5. ABS_OFFSET=0x10101010   result[04]=0x10100010
6. ABS_OFFSET=0x14141414   result[05]=0x00000000
7. ABS_OFFSET=0x18181818   result[06]=0x00000000
8. ABS_OFFSET=0x1C1C1C1C   result[07]=0x00000000
9. ABS_OFFSET=0x20202020   result[08]=0x00000000
10. ABS_OFFSET=0x24242424   result[09]=0x00000000
11. ABS_OFFSET=0x28282828   result[0A]=0x00000000
12. ABS_OFFSET=0x2C2C2C2C   result[0B]=0x00000000
13. ABS_OFFSET=0x30303030   result[0C]=0x00000000
14. ABS_OFFSET=0x34343434   result[0D]=0x00000000
15. ABS_OFFSET=0x38383838   result[0E]=0x00000000
16. ABS_OFFSET=0x3C3C3C3C   result[0F]=0x00000000
17. ABS_OFFSET=0x40404040   result[10]=0x00000000
18. ABS_OFFSET=0x44444444   result[11]=0x00000000
19. ABS_OFFSET=0x48484848   result[12]=0x00000000
20. ABS_OFFSET=0x4C4C4C4C   result[13]=0x00000000
21. ABS_OFFSET=0x50505050   result[14]=0x00000000
22. ABS_OFFSET=0x54545454   result[15]=0x00000000
23. ABS_OFFSET=0x58585858   result[16]=0x00000000
24. ABS_OFFSET=0x5C5C5C5C   result[17]=0x00000000
25. ABS_OFFSET=0x60606060   result[18]=0x01000000
26. ABS_OFFSET=0x64646464   result[19]=0x01000000
27. ABS_OFFSET=0x68686868   result[1A]=0x01011110
28. ABS_OFFSET=0x6C6C6C6C   result[1B]=0x01111111
29. ABS_OFFSET=0x70707070   result[1C]=0x11111111
30. ABS_OFFSET=0x74747474   result[1D]=0x11111111
31. ABS_OFFSET=0x78787878   result[1E]=0x11111111
32. ABS_OFFSET=0x7C7C7C7C   result[1F]=0x11111111

Board 2 (Faulty board)

1. ABS_OFFSET=0x00000000   result[00]=0x11111111
2. ABS_OFFSET=0x04040404   result[01]=0x11111111
3. ABS_OFFSET=0x08080808   result[02]=0x11110111
4. ABS_OFFSET=0x0C0C0C0C   result[03]=0x10100010
5. ABS_OFFSET=0x10101010   result[04]=0x10100010
6. ABS_OFFSET=0x14141414   result[05]=0x10100000
7. ABS_OFFSET=0x18181818   result[06]=0x00000000
8. ABS_OFFSET=0x1C1C1C1C   result[07]=0x00000000
9. ABS_OFFSET=0x20202020   result[08]=0x00000000
10. ABS_OFFSET=0x24242424   result[09]=0x00000000
11. ABS_OFFSET=0x28282828   result[0A]=0x00000000
12. ABS_OFFSET=0x2C2C2C2C   result[0B]=0x00000000
13. ABS_OFFSET=0x30303030   result[0C]=0x00000000
14. ABS_OFFSET=0x34343434   result[0D]=0x00000000
15. ABS_OFFSET=0x38383838   result[0E]=0x00000000
16. ABS_OFFSET=0x3C3C3C3C   result[0F]=0x00000000
17. ABS_OFFSET=0x40404040   result[10]=0x00000000
18. ABS_OFFSET=0x44444444   result[11]=0x00000000
19. ABS_OFFSET=0x48484848   result[12]=0x00000000
20. ABS_OFFSET=0x4C4C4C4C   result[13]=0x00000000
21. ABS_OFFSET=0x50505050   result[14]=0x00000000
22. ABS_OFFSET=0x54545454   result[15]=0x00000000
23. ABS_OFFSET=0x58585858   result[16]=0x00000000
24. ABS_OFFSET=0x5C5C5C5C   result[17]=0x00000000
25. ABS_OFFSET=0x60606060   result[18]=0x00000000
26. ABS_OFFSET=0x64646464   result[19]=0x00000000
27. ABS_OFFSET=0x68686868   result[1A]=0x00000000
28. ABS_OFFSET=0x6C6C6C6C   result[1B]=0x01001000
29. ABS_OFFSET=0x70707070   result[1C]=0x01001111
30. ABS_OFFSET=0x74747474   result[1D]=0x01111111
31. ABS_OFFSET=0x78787878   result[1E]=0x01111111
32. ABS_OFFSET=0x7C7C7C7C   result[1F]=0x11111111

[igorpadykov]

Hi Peter

results 0x10111111 are high and low failure points as described in

sect.13 Read DQS Delay Calibration AN4467 i.MX6 Series DDR Calibration

https://www.nxp.com/docs/en/application-note/AN4467.pdf 

>2) If wider the 0 window, it represent more pass results for the ddr. Is that good or bad ?

good

>4) Can we get any failures of byte lane of the memory from this results ?

these results seem as good, so from them there is no way to tell reason for linux failures.

Best regards
igor
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