Jetson Tk1, frame buffer in U-Boot

Hello!
What should be done to bring the image still at U-Boot?

If you mean what stops it from continuing boot, any keystroke. There are two points it will stop at…environment setup stage or kernel select stage. If you stop too soon just type “boot” and then hit a key again to stop at the next stage (all of course from serial console prompt, not from Jetson).