https://bugs.freedesktop.org/show_bug.cgi?id=107978
--- Comment #10 from Shmerl shtetldik@gmail.com --- I just found something. My monitor - Dell U2413 has a setting for toggling DisplayPort 1.2. It was enabled until now. When I disable that setting, tty starts working!
My cable is supposed to support DP 1.2 and be Vesa compliant. It's Accel UltraAV DP 1.2 cable.
I hope this can help narrow down the problem.