[manjaro-dev] pinebookpro-audio/snd_soc_es8316: minor issue regarding hardware codec controls

[haskal at disroot.org]

I have recently come across a solution for an audio issue i was having with my Pinebook Pro (running the stock KDE pinebook pro manjaro image), and I wanted to recommend package changes to address the issue.

The issue was relating to the sound quality with headphones when playing music on the laptop. I'm not much of an audiophile, but it became clear that the audio output for some given music with the same headphones sounded drastically different than when I played the same music on my other laptops or phone. The equalization seemed completely off, to the point of hurting my ears by over-amplifying some higher frequencies.

I dug into the es8316 codec chip and looking at the Linux driver discovered it had a hardware control for 'DAC Stereo Enhancement' -- and according to amixer it was on a scale of 0-7 and defaulted to 5. Upon disabling it with `sudo amixer sset 'DAC Stereo Enhancement' 0` the audio quality immediately became normal. Try running amixer sset on this control with various value parameters while some audio is playing and you will notice how the audio quality changes.

In short the 'DAC Stereo Enhancement' control causes audio output to sound like, to put it bluntly, hot garbage. To the point of hurting your ears. And in my opinion, it should not be enabled by default. So I wanted to propose a change perhaps to the pinebookpro-audio package to make sure the default value for this is 0, not 5. Though I'm not actually sure where the default of 5 gets set in the audio stack -- whether it's a chip default, something in the kernel driver, or something in KDE. I'm happy to do more work isolating this issue and creating the necessary merge requests if needed.

Best regards,
- haskal