imx7ulp LPDDR3 clock frequency

[kayiyeh]

I have an imx7ulpevk board, and I would like to try if I can use other DRAMs. Currently I can boot up with Linux but the system seems not very stable, I would like to slow down the DRAM frequency for debug but I don't know how. I know I should use the register programming tool (the excel file) but when I change the frequency, I didn't see any register value change. I can't find detail imx7ulp datasheet either.

[igorpadykov]

Hi Ka-Yi

i.MX7ULP documentation can be found on link

i.MX 7ULP Applications Processor | Arm Cortex-A7 + M4 with ultra-low power | NXP 

i.MX7ULP Register Programming Aids 

codes for changing ddr frequency can be found in CPUFREQ driver desribed in Linux Manual in

Linux L4.14.98_2.0.0 Documentation

Best regards
igor
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[kayiyeh]

Dear Igor,

Thank you for your information. However, what I want to do is to change DDR frequency in the beginning, say using the “Register Programming Aid” to modify registers in the beginning. But I didn’t see any meaningful register change if I change the C26 cell in the Register Configuration tab of the “i.MX7ULP1_LPDDR3_RegisterProgrammingAid_V0_3.xsel” file. And neither can I find any other cell that are related to DDR clock frequency setting. If possible, please tell me which register(s) or cell(s) is required to in the file to change DDR clock frequency.

KY

[igorpadykov]

Hi Ka-Yi

some examples can be found in

lpddr3_freq_imx.S\mach-imx\arm\arch - linux-imx - i.MX Linux kernel 

Best regards
igor