[coreboot] DP (Display Port) not enumerating in OS

[Rao G]

Hello Coreboot Developers,

Display port which comes along with Integrated LVDS, does not show up
any OS graphics display text or screen after booting to OS, the DP port
looks good
during BIOS, at some point of time during OS booting display port turns off
and no
video on DP.

Using ubuntu 18.04

Some ASL code for graphics is missing?
HDMI, DVI & LVDS works well, no issue there

Thanks for your time and any clues that would help to resolve this issue?

Kind Regards
Rao