Question/issues about i.MX6 DDR configuration

[Francesco Dolcini]

Hello Fabio,

On Sat, Dec 04, 2021 at 11:29:23AM -0300, Fabio Estevam wrote:
> Back to your original instability issue: I suppose you are talking
> about colibri_imx6.c.
Both colibri/apalis imx6 are somehow affected.

> Does it work well if you convert it to the mx6_dram_cfg() scheme?
I have not tried yet, I was trying to understand first if there are
reasons to believe that doing the MMDC initialization this way is
supposed to produce better results or it is going to be just different.

One of the problems is that the issue is not that easy to reproduce, it
seems related to some specific module/condition, I would like to avoid
doing a change that seems to solve the problem, but that in the end is
just going to hide it for a few months. I'd like to really get to the
bottom of it.

I also had a look at a NXP presentation from 2020 [1] on MMDC
calibration for mass production, but we already did something like that,
moreover we do calibrate for each board at power-up and this
should be just enough. I do not believe that this is the issue.

Francesco

[1] https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors%40tkb/335/1/i.MX6%20DDR%20calibration_stress%20for%20Mass%20Production.pdf