With Linux 5.5 kernel, pulseaudio seems to be unable to recognise a present nvidia hdmi output
Summary
Linux 5.5 has just been released, and after upgrading, I found that pulseaudio did not report is was using the nvidia hdmi output as it was before the upgrade, and it was not listed as an eligible output. Instead, it insisted the only sink it could use was the motherboard audio's SPDIF output.
After some experimentation, I found that if I force-ably set the nvidia sink's active profile to what worked before (in my case stereo on the first output), and then forced a client to use that sink, I would get audio - but I could not change the default sink, and it remained pointing to the motherboard SPDIF. I then tried unloading the module for the motherboard audio, and that finally forced the default sink over to the nvidia (although this also left pulseaudio reporting no available sinks, even while routing the audio correctly).
The big change in this area in the 5.5 kernel is the introduction of support for DisplayPort MST audio, and the output of pa-info for the nvidia card is very different when comparing 5.4 and 5.5.
We see that in the 5.4 audio, the HDMI stereo output profile is available, while with 5.5, all the profiles are marked as not available.
environment
I will be attaching pa-info
output for both 5.4 and 5.5.
Steps to reproduce
- Have a system with an nvidia graphics card
- Use the nvidia proprietary driver (no idea of that makes a difference, but it's all I have to test with)
- Observe the lack of audio and lack of willingness of pulseaudio to use the nvidia output
What is the current bug behavior?
nvidia output is considered to be unavailable, even though alsa reports the presence of the output and forcing the output usage as discussed above results in sounds being played
What is the expected correct behavior?
nvidia output can be selected as the active/default output.