ls1021a erratum 9942

[renaud]

I have the U-boot source from git://source.codeaurora.org/external/qoriq/qoriq-components/u-boot.

I was wondering why for the ls1021a board support (IOT, TWR, QDS, TSN), only the QDS calls erratum_a009942_check_cpo.

I did notice that part of the erratum 9942 is done in the DDR driver.

Cheers,

Renaud

[Chavira · Accepted solution]

Thank you for contacting NXP support!

The errata is board dependent, it's related to the DDR design on board. On ls1021aqds, it uses DDR3L UDIMM/RDIMMs, but on ls1021atwr, it uses DDR3L SDRAM discrete devices. The workaround is needed on ls1021aqds, but not needed on ls1021atwr. As for IOT/TSN board, they're not the mainstream boards included in LSDK release, I didn't use them before, I guess they don't need to apply it.

/*
* This additional workaround of A009942 checks the condition to determine if
* the CPO value set by the existing A009942 workaround needs to be updated.
* If need, print a warning to prompt user reconfigure DDR debug_29[24:31] with
* expected optimal value, the optimal value is highly board dependent.
*/