Comment 9 for bug 1970050

Fixed on my system (i7-4790s haswell, ubuntu 22.04) with previous kernel update (uname -r -> kernel 5.15.0-40-generic). Before on my system HDMI output might produce little sound and then the audio seemed to stop buffering sound completely (resulting in output fail, stopped video or other weirdness).

intel_iommu=on,igfx_off grub-trick would fix the issue, now I've got GRUB_CMDLINE_DEFAULT="" in grub params and HDMI works; if I remember correctly the patch notes for the kernel said IOMMU is now disabled by default on some systems?

For me the problem was never an issue with recognizing connected HDMI audio outputs.