Just like UnlikelyLass, I’m seeing the same looping messages over UART and a blank screen when I boot. I thought it was a hardware issue with my DSI to eDP chip, but since other people are having the same problem I am not so sure any more. My post is here. Reform SN65DSIx6 DSI to eDP is NAK'ing On Boot
When you break out the UART adapter, maybe you can grep for this?
ti_sn65dsi86 1-002c: error -ENXIO: failed to read device id
I’ll try downgrading to a 6.15 kernel.