I have a board already supported in U-Boot based on the i.MX8MM with LPDDR4, and with a simple part change, we have built a Nano version as well with the same LPDDR4.
I have mostly copied the imx8mn EVK files to the board support, and migrated the device tree files for my board. I also created a lpddr4 cfg file for the i.MX8MN because it appears to have a different bootloader than the Mini, but I am referencing the LPDDR4 training files used on the 8MM.
Unfortunately when I boot, I get a boot-loop with output that looks like this:
U-Boot SPL 2020.07-00499-gd9107930af-dirty (Jul 10 2020 - 09:47:31 -0500) spl_init
SPL: board_init_r()
Normal Boot WDT: Started without servicing (60s timeout) Trying to boot from BOOTROM image offset 0x8000, pagesize 0x200, ivt offset 0x0 board_fit_config_name_match: imx8mn-beacon-kit Selecting config 'imx8mn-beacon-kit'outname = uboot@1 board_fit_config_name_match: imx8mn-beacon-kit Selecting config 'imx8mn-beacon-kit'outname = fdt@1 board_fit_config_name_match: imx8mn-beacon-kit Selecting config 'imx8mn-beacon-kit'outname = atf@1
U-Boot SPL 2020.07-00499-gd9107930af-dirty (Jul 10 2020 - 09:47:31 -0500) spl_init ...
I was curious to know if any of the NXP people might have any suggestions on what I might try. I have tried building the imx8mn evk and modifying the Kconfig to reference LPDDR4 instead of DDR4, and pointing to the cfg file for lpdd4 on the 8mn. Unfortunately, I don't see any change.
I have also tried the NXP repos on Code Aurora going to releases as far back as 4.19_1.10, without success. I see the standard imx8mn_evk appears to use lpddr4, but that board doesn't appear upstream. Does that board exist?
thanks,
adam