i.mx28 u-boot dram configuration for dram replacement.

[RandyGraham]

Hello,

We have a custom i.mx28 board based on the mx28-evk reference design.

My hardware guy tells me that the dram chip used on the m28-evk board is no longer available and we need to use the micron equivalent, http://www.micron.com/~/media/Documents/Products/Data Sheet/DRAM/512MbDDR2.pdf, which is what we have on our custom board .

We are having issues getting u-boot to come up on our board, so I was wondering, should I need to adjust the dram configuration settings for this memory replacement ?

I'd assumed not since it should be functionally equivalent.

u-boot appears to initialize power, clocks, etc fine from SRAM but resets when relocating and trying to run from DRAM which is why I think we have a dram issue.

All of our voltages look correct.

Hopefully I am not asking a silly question :smileyhappy:

-Randy

[Yuri]

I.MX28 DRAM system (under Linux) is initialized in bootlets, and strictly speaking

for new memory it is needed to provide some adaptation.

Source codes are located in

<ltib>/rpm/BUILD/imx-bootlets-src/boot_prep/init-mx28.c 

To get it, please use the next commands 

./ltib -m prep -p imx-bootlets-src

After editing :

./ltib -m scbuild -p imx-bootlets-src

./ltib -m scdeploy -p imx-bootlets-src

Next, please use the tool, linked below, to get optimal settings for specific DRAM :

Board_bring-up_and_DDR_initialization_tools :

https://community.freescale.com/docs/DOC-1455

https://community.freescale.com/wiki/images/1/15/MX28_DRAM_controller_register_programming_aid_v4.tar.gz

And finally, based on fact that both memory chips (old and new) are practically the same - perhaps
it makes sense to test memory (to avoid design or manufacture issues).

[RandyGraham]

Thanks Yuri !

I am not using LTIB, but rather building the mainline u-boot directly.

Thanks for the doc and programming aid, I'll take a look.

-Randy