[DEBUG] rk3399-nanopi-neo4: SPL SD init may report -5 due to SD power-on timing

[Sune Brian]

> Your original mail mentions "sometimes fails" and that you tested U-Boot
> v2026.01-rc1+, the most recent change for the nanpi4 family was related
> to sd-card regulator handling to improve reboot when card was using uhs
> speed in os and boot fails in spl due to this.

I cant 100% conclude all boards and situations so I used "sometimes".

> Please try my suggestion above, the datasheet for the LDO mention 50us
> start-time and card may need one ms to fully init. Defining this timing
> requirement in the device tree that U-Boot SPL uses should match the
> workaround/fix you mention in your original mail.

w/o modification do your board experience any sd card error or stall during
boot phase?

brian