I recently purchased an Inspiron 7591 laptop and although Ubuntu wasn't offered pre-installed I was told by Dell customer service that I would be able to install it fine myself, which I did. After installing ubuntu 19.10 the sound and microphone were not working. In the sound menu it had "dummy output", and nothing for input. Today I upgraded to Ubuntu 20.04 LTS and have found the same issues.
While I have found a fix-around to get the sound working I don't have complete faith in it, and the microphone still does not function. It would be nice if there was an official fix from Dell as I don't seem to be the only person experiencing this.
There is an issue with microphone autodetection - I use the 3,5 mm 3 pin jack as AUX to my tower, but when I connect it, Kubuntu switches from Internal Microphone to Microphone and disables all output, and even worse, the tower randomly starts/stops brumming whatever I will set as microphone input until I set input to Internal Microphone and start playing something, then brumming stops.
When I use 4 pin jack with splitter to microphone and 3 pin output, suprisingly everything behaves the same (wrong) way (brumming + Kubuntu automatically switched to Microphone even when it is not connected).
I have no idea if it is some firmware/bios/OS issue, but probably ... I would blame Ubuntu for that.
I have Dell 7740,
cat /proc/asound/card*/codec* | grep Codec
codec Realtek ALC289
For those of you who have Ubuntu, you have three options to fix this:
1.) Apply this patch and reboot: https://launchpad.net/~kaihengfeng/+archive/ubuntu/fix-lp1869819
2.) Else, enable 'Pre-released updates (focal-proposed)' under Developer options in Software & Updates. Update and reboot.
3.) Else, wait for the next PulseAudio update.
I tried 18.04 on 7591 .. Wifi doesn't work, sound doesn't work at all.
on 20.04 Wifi works, but it's not stable.
Not sure why this is listed as compatible with Ubuntu.