HDMI sound not available

Brief summary of the problem:

The HDMI audio output device is no longer available on newer kernels. My speakers are plugged into my monitor. My monitor is plugged into my RX 5700 XT via DisplayPort. After upgrading my kernel, I noticed I can no longer select the Navi HDMI output device for sound. When booting into older kernels, I can select Navi HDMI as my output device and audio plays through my speakers.

Kernel v5.10 is good: Navi HDMI output is available and works.

Kernel v5.11 is bad.

The latest tag on linux-next (next-20210319) is bad.

The tip of Linus's mainline tree is also bad.

I attempted a bisection between v5.10 and v5.11 but when I got down to the last few kernels, a separate issue prevented any further progress. The boot process would hang and the last message was: "switching to amdgpudrmfb from efi vga", so I was unable to actually get into my desktop environment and test if the commit was good or bad. :(

Hardware description:

• CPU: AMD Ryzen 5 3600
• GPU: AMD RX 5700 XT
• System Memory: 16 GiB
• Display(s): Dell P2715Q - 4k@60hz, 200% DPI scaling
• Type of Diplay Connection: DP

System information:

• Distro name and Version: Fedora 33
• Kernel version: 5.10.23-200.fc33.x86_64 (GOOD) 5.11.7-200.fc33.x86_64 (BAD)
• Custom kernel:
• AMD package version: ??

How to reproduce the issue:

1. Boot into kernel
2. (I'm using the KDE environment) Select the "sound" icon in the task bar

expected result: Navi 10 HDMI out is present. When selected, audio plays through the output device (speaker-test -c 2 or pull up a video or song and verify).

actual result: Navi 10 HDMI out is not present as an audio device. When digging through menus, it is shown as "off" with no dialog option to enable.

$ cat /sys/module/amdgpu/parameters/audio
-1

bisect-log-20210321-2

I have attached my latest bisect log. Towards the bottom the "skips" are for kernels where I couldn't boot.