My HDMI audio, which was previously working with Ubuntu 20.04 on my Lenovo W540 laptop while docked and attached to my Benq external monitor is no longer available as a sound device.
I am using the NVidia GK106GLM driver (nvidia-driver-390) for the built-in Quadro K2100M GPU.
It is not that the sound is no longer working, but within the last week or two the HDMI output device is not even appearing in my Sound Control Panel selection list. I can not even select it because it is no longer listed. I just recently noticed this as I have been travelling and did not have a chance to re-dock my laptop at home until now, so I am uncertain as to when the option disappeared.
Nothing has changed physically (same dock, same cable, same monitor), so I am fairly certain that it is a software issue. I do not remember seeing an NVidia update, but I seem to remember an ALSA update. I can't be certain, though, because I was away from the docked setup and did not notice it for weeks.
I checked the configuration for the HDMI audio driver with the Pulseaudio Volume Control app and found that the GK106 HDMI Audio Controller
reports all HDMI options as (unplugged) (unavailable)
:
Digital Stereo (HDMI) Output (unplugged) (unavailable)`
Digital Stereo (HDMI2) Output (unplugged) (unavailable)`
Digital Stereo (HDMI3) Output (unplugged) (unavailable)`
Digital Stereo (HDMI4) Output (unplugged) (unavailable)`
Digital Surround 5.1 (HDMI) Output (unpluggeed) (unavailable)`
Digital Surround 5.1 (HDMI2) Output (unpluggeed) (unavailable)`
Digital Surround 5.1 (HDMI3) Output (unpluggeed) (unavailable)`
Digital Surround 5.1 (HDMI4) Output (unpluggeed) (unavailable)`
Digital Surround 7.1 (HDMI) Output (unpluggeed) (unavailable)`
Digital Surround 7.1 (HDMI2) Output (unpluggeed) (unavailable)`
Digital Surround 7.1 (HDMI3) Output (unpluggeed) (unavailable)`
Digital Surround 7.1 (HDMI4) Output (unpluggeed) (unavailable)`
Not sure if this is relevant or not, but the Built-in Audio
device also reported the above options, but ALSO included an (HDMI5)
in the list (3 additional entries, one for each of the Stereo, Surround 5.1, and Surround 7.1)
I have tried reinstalling pulseaudio, but it did not help:
sudo apt-get install --reinstall alsa-base pulseaudio
sudo alsa force-reload
Any ideas on why HDMI audio is reporting (unplugged) (unavailable)
and is no longer listed as an output device?