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iMX6 DDR3 Calibration

Question asked by Inderjit Bains on Mar 23, 2016
Latest reply on Mar 28, 2016 by igorpadykov

I have two i.MX6 boards, with a total of 2GB DDR3 SDRAM (4 x 4GBit), 64-bit bus.  I used the DDR Stress Tool V2.51 to calibrate the DDR, running from an SD card, using the following commands in u-boot:

 

u-boot> dcache off

u-boot> icache off

u-boot> fatload mmc 1:1 0x00907000 ddr-test-uboot-jtag-mx6ul.bin   

u-boot> go 0x00907000

 

For Board #1, the calibration always succeeds.  For Board #2, the calibration sometimes fails (~one time of out ten) on:

 

DDR Calibration failed during Read calibration: 

ABS_OFFSET=0xNNNNNNNNN   result[MM]=0x11111111

 

The result is 0x11111111 for the entire run of DDR Calibration failed during Read calibration.

 

Using the average calibrations from Board #1 and Board #2 (for the successful calibrations), both boards pass the DDR stress test, which was run for 3 hours.  Any idea why Board #2 sometimes fails calibration?

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