I have a Lenovo P50 which contains an NVIDIA Quadro M2000M in reverse PRIME configuration: The HDMI port is connected to the NVidia card. While getting an image onto the HDMI port works just fine, there is no audio.
I asked about this on IRC, the logs are at <https://people.freedesktop.org/~cbrill/dri-log/index.php?channel=nouveau&highlight_names=&date=2017-11-24#t-2034>. The summary is that I tried running the following script (after stopping X):
setpci -s 01:00.0 0x488.l=0x2000000:0x2000000
echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove
#echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan
echo 1 > /sys/bus/pci/rescan
But that did not help. I then started X again, and lspci still shows only
$ sudo lspci -nn -d 10de:
01:00.0 VGA compatible controller : NVIDIA Corporation GM107GLM [Quadro M2000M] [10de:13b0] (rev a2)
-- GitLab Migration Automatic Message --
This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.
You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/xorg/driver/xf86-video-nouveau/issues/384.