No HDMI Video, or with HDMI Video/Audio but no internal display

[chaihaixin]

as title.
typically when i plug HDMI, internal display goes off, and no HDMI video at all. when unplug-HDMI, the LCD remain off.
Occasionally, there will be HDMI video+audio correctly, but internal LCD always off.
Never success when plug HDMI during boot up, both screen remain off.

Thinkpad x1c 2017, HD620, 2 TB3, 1 HDMI, checked within windows internal LCD is eDP.
tried eDP patch manually (change port type from 20 00 00 00 to 00 04 00 00 but this issue remains, do solve some lid close/reopen issue, but unstable)

thanks for any hints.

Sorry ioreg can't reflect HDMI port - in some rare case (with display) it shows it connect to framebuffer@1

 

[RehabMan]

as title.
typically when i plug HDMI, internal display goes off, and no HDMI video at all. when unplug-HDMI, the LCD remain off.
Occasionally, there will be HDMI video+audio correctly, but internal LCD always off.
Never success when plug HDMI during boot up, both screen remain off.

Thinkpad x1c 2017, HD620, 2 TB3, 1 HDMI, checked within windows internal LCD is eDP.
tried eDP patch manually (change port type from 20 00 00 00 to 00 04 00 00 but this issue remains, do solve some lid close/reopen issue, but unstable)

thanks for any hints.

Sorry ioreg can't reflect HDMI port - in some rare case (with display) it shows it connect to framebuffer@1

Read here regarding EDID override:
https://www.tonymacx86.com/threads/readme-common-problems-in-10-13-high-sierra.233582/