How to set HDMI output resolution with FBDEV on Beaglebone Black?

I’m completely new, but I was wondering whether you could explain how your comment relates to @RobertCNelson 's comment in https://forum.beagleboard.org/t/how-to-fix-no-hdmi-output-with-4-19-94-ti-r42-crash-on-mouse-move-with-4-19-94-ti-r71/31520/9:

The the modesettting driver has a long history of hard locking the am335x when used… The system would hardlock, nothing would work… Serial, etc ends up just dead

Shall one use “fbdev” or “modesetting” in Xorg.conf? And how to decide?