No 5.1 sound on hdmi outputs for laptop

I have a Lenovo Yoga C940 laptop, which has HDMI capabilities. In standard Fedora 37 with pipewire, pulseaudio, etc. (and XFCE, but that shouldn’t matter) I can output stereo sound to my A/V receiver and hear it on my speakers.

What I can’t do is send 5.1 sound. The hardware is all there but there doesn’t seem to be any support for anything other than stereo sound for audio output from applications like Firefox or vlc or speaker-test. The sound is always mixed down to two channels.

What is the bottleneck and is there some way to break it open? I see the following hardware devices using aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: sofhdadsp [sof-hda-dsp], device 0: HDA Analog () []
Subdevices: 0/1
Subdevice #0: subdevice #0
card 0: sofhdadsp [sof-hda-dsp], device 3: HDMI1 (
)
Subdevices: 0/1
Subdevice #0: subdevice #0
card 0: sofhdadsp [sof-hda-dsp], device 4: HDMI2 () []
Subdevices: 0/1
Subdevice #0: subdevice #0
card 0: sofhdadsp [sof-hda-dsp], device 5: HDMI3 (
)
Subdevices: 0/1
Subdevice #0: subdevice #0
card 0: sofhdadsp [sof-hda-dsp], device 31: HDA Analog Deep Buffer (*)
Subdevices: 1/1
Subdevice #0: subdevice #0

Does anyone know how to enable 5.1 audio to my HDMI output?