RTX 2060 Mobile audio device only temporarily available

[wiro-i]

My endeavor began trying to get a display output via my HDMI port. At least this part, I was able to solve via an X org configuration. The file is accessible in the nvidia-bug-report.log.gz on line 3844.

While I tested the setup, I noticed that I could not select the connected device as an audio output. My research led my to this forum thread that discussed this issue. First, I followed the steps outlined in the as solved marked post. Yet I could not get the audio device to show up in lspci.

To try another way to do the same thing, I installed the nvhda kernel module found here. Sadly, that did not fix it either.

So I went locking through my kernel log. In there I at least found evidence, that the audio device exist (I wasn’t sure about that which might be a little dumb). nvhda was also able to set the magic bits, at least sometimes. It finds and losses the graphics cards a couple of times during boot up, though that is probably not the issue.

Further down the log, I found something that looks suspicious to me. I copy the segment here, but you can also find it on line 7608.

[ 497.428551] input: HDA NVidia HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input23 [ 497.428615] input: HDA NVidia HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input24 [ 497.428662] input: HDA NVidia HDMI/DP,pcm=8 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input25 [ 497.428743] input: HDA NVidia HDMI/DP,pcm=9 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input26 [ 497.428793] input: HDA NVidia HDMI/DP,pcm=10 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input27 [ 497.428841] input: HDA NVidia HDMI/DP,pcm=11 as /devices/pci0000:00/0000:00:01.1/0000:01:00.1/sound/card1/input28 [ 497.630568] pci 0000:01:00.1: Removing from iommu group 10

To me that looks as if the audio device of my graphics cards gets recognized and properly setup. But afterwards, for some reason, it gets removed by something.

Is someone able to tell why, or can point me in a direction where I can investigate further?

If you need further information, I am happy to supply them,
and thank you for reading the whole post.

LOG: nvidia-bug-report.log.gz (262.1 KB)
Note that the second display device was plugged in while my Laptop booted.

[wiro-i]

It has been a while, and in the meantime I have found the particular problem in my case. I write this reply as documentation for future users that might have a similar problem.

In my case, the problem was caused by a udev rule that removed the audio device of the graphics cards. To find the file that contains the rule, you can execute the following command:

grep -r -l "0x040300" /etc/udev/

A short explanation on what the command does. grep searches for strings/text/regex in files. If you have never heard of it, please look it up and learn how to use it. It is very useful, especially in conjunction with regular expressions (regex). -r searches through all files recursively starting at the specified path /etc/udev/ where udev rules are stored. -l outputs the name and path of the file in which a match is found instead of the line in the file with the match. The characters "0x040300" is the string grep looks for in files and is the class of the PCIe device to which the rule applies.

Open the file printed to the terminal in a text editor and comment out the offending rule (by inserting # at the beginning of the line). If the command found multiple files, you should check in the rule if the vendor attribute is set to "0x10de" (for example, the rule must contain ATTR{vendor}=="0x10de" to be the appropriate one).

Now the audio device show up in lspci and I can select it as output when an HDMI cable is connected.