Normal baudrate for Rockchip boards

[z4v4l]

Thank you all. I actually fixed it yesterday, it was too late to post about it. I added a couple of lines in the /boot/boot.cmd (I use Armbian) and recompiled it. Those changes set on the fly new baudrate for UART2 in related properties in two nodes of the DT (this file, lines 52 and 62). Also set uboot's "baudrate" and it works now. Both uboot and linux use 115200 baud/s speed. I only get some little amount of boxes at the very beginning of the boot, this is most probably ROM code output, but it's tiny, it's tolerable. But now I can use Rock64 with an adapter, that doesn't support 1500000 baud/s but otherwise is very good, and most importantly - that I can directly insert into my computer.