DP Audio does not unmute after DPMS off/on


I have a K420 quadro card, using 364.19 driver to drive a single UHD screen (PHILIPS/BDM4065UC) over DP. The screen has built in speakers and sound (pulseaudio) over the DP works fine

However when I run a screensaver that blanks the screen via dpms (e.g. i3lock -d or xscreensaver) or a simple

xset dpms force off

the display blanks and sound mutes. When I unblank the screen the video comes on fine, but the audio stays muted.

I don’t have a simple command that starts the audio, but starting (or restarting) xscreensaver does unmute the audio, presumably because it re-initialises the DPMS config in some way (?).

Not sure if this is a bug in the driver?

Does anyone have any suggestions for further investigation?
nvidia-bug-report.log.gz (202 KB)