This is a regression and someone has bisected it to ef6f5494faf6a37c74990689a3bb3cee76d2544c[0]. There is additional discussion on Arch linux's bug tracker[1] and forums[2] about the issue. In particular, multiple confirmed fixes when reverting ef6f5494faf6a37c74990689a3bb3cee76d2544c. I can confirm that the commit reverted fixes my issue with my Ryzen 5 PRO 6650U CPU and radeon 680M GPU. I'm unsure what debug logs are useful here, but I'm willing to provide them as needed. I could not notice anything different in dmesg/udev between 6.0 and 6.1. [0] https://github.com/torvalds/linux/commit/ef6f5494faf6a37c74990689a3bb3cee76d2544c [1] https://bugs.archlinux.org/task/76917 [2] https://bbs.archlinux.org/viewtopic.php?pid=2075553#p2075553
It's worth noting that the PCIe devices don't even show up with that commit applied, it's not that HDMI audio won't output, it's that the devices themselves *do not exist*. So it makes sense that this commit, which touches on enumeration of the devices, seems to have caused this regression.
*** This bug has been marked as a duplicate of bug 216836 ***