Kernel and device tree independence

I thought one of the advantages of the device tree setup was that it was independent of the kernel,
but apparently a fair amount of porting work is still needed between kernel versions. Does anyone
know how roughly how much of a DT can be kept, from kernel to kernel?

Will

Give it another year or so, some DT bindings are frozen, but some are
still in flux. kernel developers are planning to eventually move the
dts's to a separate repo, when that actually happens, you'll have the
answer your looking for.

Regards,

I do have the same issue. I want to use UART1 and UART4 with RTS.
It is not possible to add a modified device tree of UART4 to uEnv.txt because it shows an error on startup. But it works when I do it manually after the system booted up.
Additionally I can not use UART1 because I2C2 blocks the RTS pin.

Do you know a solution, Robert?