+LTS/SOPINE how to change for init status of gpio

[chun jong rock]

I have two further questions.
I try to convert the dtb to dts. and check the dts file. but there is not about changing the status of default gpio.
so I didn't make it that you told me the one way.

and the other way is using a u-boot.
I have searched the way for installing a u-boot but I can't find the way.

Could you tell me the site of installing a u-boot in a64.
additionally, if you can check the first question, tell me the way plz.

Thanks.