No HDMI sound with older Nvidia card (nouveau driver)

Support and Help
1

Hello,
I have a PC to run MythTV so sound ( and video) is obviously very important. I have recently changed the 17 year old motherboard so that I can update to Ubuntu 24.04 but have kept the Nvidia GT710 video card. This card is old but works absolutely fine in 22.04 for both sound and video, using the nouveau drivers (too old for the Nvidia drivers).

So, all working nicely in 22.04 but as soon as I upgrade to 24.04 the sound stops working. In the sound settings the card is still listed but the test option yields no sound.

I have also tried changing the video card for another older Nvidia card, GeForce GT 610, with the same results.

I have now done some fairly extensive testing by triple-booting this machine between Ubuntu 22.04, Ubuntu 24.04 and Debian 12. I noticed that the Debian install played sounds absolutely fine so I looked at the kernels on each of these 3 boots:

Ubuntu 22.04: 5.15.0-126 (HDMI sound works)
Ubuntu 24.04: 6.8.0-49 (HDMI sound not working)
Debian 12: 6.1.0 (HDMI sound works)

I then did some experiments to gradually update the kernel on 22.04 to see if the sound would break. Sure enough, the sound worked fine all the way up to kernel 6.6.63 (the last mainline kernel available before 6.7.0) in 22.04. As soon as I tried kernel 6.7.0 the sound stopped working.

I then rebooted to 24.04 and tried downgrading the kernel to 6.6.63 and sure enough, the sound started working! I then changed it to 6.7.0 and again, no sound.

So, to sum up:

Ubuntu 22.04 and Ubuntu 24.04

kernel 6.6.63 and below - sound works well over HDMI
kernel 6.7.0 and above - no sound over HDMI

I have scoured this forum, askubuntu and others for help with no sound over HDMI on 24.04 but none of the solutions have worked until I played around with the kernels.

I’m no expert but it sounds to me like this is a problem with kernels from 6.7.0 onwards. These video cards are less than 20 years old and perform absolutely fine if you’re not a gamer so I would really like them to work.

But as a Linux user with no coding or development experience, I have no idea how to follow this up. Help please!

Thanks

2

Have you tried using the search for 3rd party drivers option on the newer kernel? Maybe support was moved out of the kernel, but there is a package that has the relevant driver and/or firmware.

3

Thanks for the suggestion. However, wouldn’t the device just not show at all up in the Gnome Settings if it had no driver? And isn’t this what the Nouveau drivers are all about? As the official Nvidia ones no longer support these cards, despite only being first produced in 2012 and 2014. And there are so many much much older devices supported in the kernel than these two cards.

Looking at https://kernelnewbies.org/Linux_6.7#Graphics, there is no mention of anything being (deliberately) removed.

Also the messages in dmesg for the card are the same in 22.04 and 24.04 and yet sounds works on one and not the other:
[ 8.583009] [drm] Initialized nouveau 1.3.1 20120801 for 0000:01:00.0 on minor 0

Out of interest, any idea where I might find such 3rd party drivers? And what do you mean by “3rd party”?