[BUG] i915 HDMI connector status is connected after disconnection

[Chris Chiu]

Hi,
    We have few ASUS laptops X705FD (The new WiskyLake), X560UD (intel
i5-8250U), X530UN (intel i7-8550U) share the same problem, which is
the HDMI connector status stays connected even the HDMI cable has been
unplugged. Look into the "/sys/class/drm/card0-HDMI-A-1/status" for
checking the status while plug/unplug the HDMI, it shows
"disconnected" before plug in HDMI cable, then switch to "connected"
after plugin, and still stay "connected" after unplug. This would
cause the audio output path cannot correctly switch from HDMI to
internal speaker after unplugging the HDMI.

I then try to verify with the latest kernel 4.18.0-rc3+, the bug still
present. The full "dmesg" log is here.
https://gist.github.com/mschiu77/d761d7c5cf191b7868d4d7788ae087f1

The HDMI cable is plugged in at ~26th second.
"[ 26.214371] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
audio support"
then unplug the HDMI at ~73th second.
"[ 73.328361] [drm:drm_detect_monitor_audio [drm]] Monitor has basic
audio support"

Please advise what I can do to fix this. Thanks

Chris