[alsa-devel] [PATCH v3 4/4] ALSA: hda - Add DP-MST support for NVIDIA codecs

[Takashi Iwai]

On Sat, 01 Feb 2020 16:28:08 +0100,
Martin Regner wrote:
> 
> Hi there,
> 
> since i updated to kernel 5.5 i have no sound over hdmi anymore (GeForce RTX
> 2070).
> 
> With the previous kernel 5.4.14 everything is fine.
> 
> Although i got sound with speaker-test -D hdmi:CARD=NVidia,DEV=2 -c 2 -r
> 44100, pavucontrol shows all hdmi sound devices as unplugged.
> 
> I bisected it down to this commit (5398e94fb753d022301825ebfa5f7cf8a660d8eb)
> and changed the line
> 
> HDA_CODEC_ENTRY(0x10de0093, "GPU 93 HDMI/DP",  patch_nvhdmi)
> 
> to
> 
> HDA_CODEC_ENTRY(0x10de0093, "GPU 93 HDMI/DP",  patch_nvhdmi_legacy)
> 
> Now it's working again. I'm not sure if this is a problem with pulseaudio or
> if the RTX 2070 does not support the mentioned codec.

The runtime PM turns off the link, so the hotplug notification won't
be delivered as default.  Please try reading the corresponding proc
file, /proc/asound/card*/codec* file.  This may power up the codec and 
trigger the hotplug detection if that's the cause.


Takashi