[U-Boot] Updating uboot from 2015.04 to 2017.03 - doubts and other questions

[Nemanja Savic]

Hi all list members,

this is my first post. I am almost new to u-boot, which means that a few
times in my life I had tasks to implement some commands and perform
initialization of GPIOS, etc. In summary very simple tasks. Now I have a
bit harder tasks - to update from version 2015.04 to 2017.03. The board is
based on i.mx6 Sabre Auto DualLite, so I am speaking of fscl u-boot.

I would like to clarify a few things:
1. When previously dealt with u-boot, the configuration of the board was
done by using #define SOMETHING. As far as I could see, u-boot is now able
to read the device tree and to load drivers based on that. Is this
preferred way of configuring u-boot now? If yes where can I find more
information about this with some examples. The thing is, my device tree has
gpio-led entry, but unfortunately i don't see debug messages I am printing
withing driver probe function (I print usinf printf, maybe other way of
printing should be used).

2. How not to use device tree for loading drivers at all? When I set
CONFIG_OF_CONTROL=n
I am not able to compile the code.

3. Is device tree used by u-boot the same device tree later used by linu
kernel?

4. How can to know if I should use menuconfig or not?

Thank you very much I hope we will have a great time in the list :D