STM32MP157F-DK2 unresponsive whenever weston is stopped

[Phaserblast]

Hey all, I'm trying to test DRM/KMS on an STM32MP1 board, but I can't do this while weston is taking over DRM. The documentation says to quit weston, then run any KMS stuff while it's not running. This is all well and good, and this is the way it's supposed to work on any Linux system, but any time weston leaves the screen, the board becomes unresponsive.

EDIT:

I built my own kernel image, and it's is working now.