Hi,

> I was thinking about taking the math from the U-Boot and porting it to
> Linux to see if the issue goes away, but before I did that, I was
> hoping someone might have some insights to see if that's the right
> direction to go.

Thank you very much for your detailed report!

I have one SanDisk card which sometimes fails to probe on one specific
board, so for me it was really hard to debug the issue because it was
hardly reproducible. Can you tell me which cards fail and if they do
that realiably? Also which Renesas HW do you use?

So much for a first response. I will have a closer look at your findings
tomorrow.

Thanks again,

   Wolfram