DDR Utility can't turn on ddr clock

[dkal]

I am testing our custom board with stm32mp153a and I have customized the DDR utility so that the uart and pmic work.  I have used the RAM timings from cubemx that kind of work with TF-a.  I have the PLL2 values that also work with TF-a.  I get a DDR Initialization KO.  Looking deeper into it, it dies when trying to turn on the DDR clock.  One thing I noticed is that the code is hard coded to use HSE when this design uses HSI for the DDR clock.  If I change it to HSI the utility gets stuck trying to print anything to UART.

[PatrickF · Accepted solution]

Hi @dkal 

Using DDR with HSI as root clock is not possible (even if path exist to PLLs) because HSI is not stable enough (frequency an jitter) to fit USB and DDR JEDEC requirements.

Regards

[dkal]

Thank you, I got the design ioc file with HSI selected and params selected for the clock so those were the numbers I used for PLL2.  I selected oscillator for HSE in the RCC settings and found the proper params for the clock, put those in the DDR suite and I am able to run the DDR tests now.