i.MX6 Boot Issue in Production Boards

[ratheeshchandra]

We have designed SoM based on i.MX6 Quad processor (PN; MCIMX6Q6AVT10AD) with 1GB DDR3 ( PN: IS43TR16128B -125KBLI). The DDR3 is routed in T-topology, with 4x DDR3 devices. The board is in production. 

Our issue is that 20% of the modules fails to boot during production test. We have to re-try DDR calibration to make these modules passed. I am just wondering , is it normal to do a DDR calibration for each production lot? ( even if I don't change any design or component etc)

Recently we build 1000 modules together. We did a DDR calibration for this batch. But still all module built on this batch doesn't boot well with this DDR calibration setting..

We are using u-boot version:

u-boot-fslc_v2013.04-r0

[igorpadykov]

Hi Ratheesh

may be recommended to try nxp uboot from source.codeaurora.org/external/imx/uboot-imx repository

uboot-imx - i.MX U-Boot 

with latest ddr test i.MX6/7 DDR Stress Test Tool V3.00 

When running a calibration test, one gets the minimum value for which the test works,
the maximum value for which the test works, and the center point. Average together
all the centerpoint value to come up with the ideal setting, and then just make sure
that value is a good margin away (~12) from any of the minimum and maximum
values observed under any conditions.  Take a random sample of 5 - 10 boards and
run the stress test a few times on each board (~5). One can run the test at extreme
temperatures as well.

Best regards
igor
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