[U-Boot] Issues when saving environment in RK399 RockPI 4

[Ezequiel Garcia]

I decided to test latest U-Boot, following instructions in
doc/README.rockchip. The instructions seemed
clear and I could build this easily.

However, there seems to be an issue when I save the environment. Any ideas?

=> saveenv
Saving Environment to MMC... Writing to MMC(0)... OK
=> reset
resetting ...
U-Boot TPL 2020.01-rc1-00213-g0f282c1876af-dirty (Nov 07 2019 - 15:21:44)
Trying to boot from BOOTROM
Returning to boot ROM...

U-Boot SPL 2020.01-rc1-00213-g0f282c1876af-dirty (Nov 07 2019 - 15:21:44 -0300)
Trying to boot from MMC2


U-Boot 2020.01-rc1-00213-g0f282c1876af-dirty (Nov 07 2019 - 15:21:44 -0300)

Model: Radxa ROCK Pi 4
DRAM:  2 GiB
Cannot find regulator pwm init_voltage
MMC:   dwmmc at fe320000: 1, sdhci at fe330000: 0
Loading Environment from MMC... OK
In:    serial at ff1a0000
Out:   serial at ff1a0000
Err:   serial at ff1a0000
Model: Radxa ROCK Pi 4
## Error: Can't overwrite "serial#"
## Error inserting "serial#" variable, errno=1
initcall sequence 000000007ffc10b8 failed at call 0000000000202a20 (err=-1)
### ERROR ### Please RESET the board ###