Missing magic in i915kms.ko?

I can use beep -d /dev/dsp0 or /dev/dsp1 and hear a sound at the rear or 
fron audio jacks.

If I send the beep to /dev/dsp2, I hear nothing.

I believe there is missing magic in i915kms.ko that routes audio from 
the video driver to the audio driver.  Or perhaps I need a hint in 
/boot/loader.conf or /boot/device.hints?

I am using the snd_hda.ko driver in FreeBSD-14p6.

I also have linuxkpi_hdmi.ko in kldstat.

I can't find man pages describing these components.  There are man pages 
for drm and drm-kms, but they don't contain magic, like loader settings 
or device hints.

I haven't been able to get sound from FreeBSD on this system for years.  
Linux Mint, KDE Neon, and Ubuntu 24.04  DO deliver sound to the hdmi/dp 
port.