Created attachment 101987 [details]
dmesg

When powering on a PC with radeon gpu (E350 in this case), without an output
device powered on (on the hdmi out), X won't start.
Therefore using drm_kms_helper to overwrite the edid information and forcing
the display to on is needed.

In this combination the hdmi audio output is not working.
It also is not working if the system is started with the overwrite in place and
TV / AVR turned on.
It seems as if the audio codec is not enabled when EDID is loaded with
drm_kms_helper

Expectation: Audio will continue to work when overwriting EDID with
drm_kms_helper.