[HDAudio][ALC295] speakers not working on Acer Travelmate P614

[Stanislav Kazmin <stas.kazmin@gmail.com>]

Hello, I have the following problem on my Acer TravelMate P614-51T-G2:

I have all the audio sinks correctly identified (like HDMI, DMic, Headphones) 
but the internal speakers do not produce any sound.

What I have tried so far:

- hard/soft shutdown on Windows and reboot
- disable/re-enable speakers and microphone in BIOS
- uninstall pulseaudio and test alsa alone (so it is defeitely **not** a 
pulseaudio issue)
- switch from sof-hda-dsp to snd-hda-intel driver (without Dmic support)
- retask pins 0x14, 0x16, 0x1b to "Internal Speakers" through hdajackretask 
(only basic, without advanced features)
- removed/reconnected the headphones

`alsamixer` shows all needed sinks and nothing is muted.

I already discussed the issue at sof github https://github.com/thesofproject/
sof/issues/3058 but since the same issue occurs on `snd-hda-intel` legacy 
river, I was advised to communicate with alsa-devel team.

The alsa-info.sh result are linked at http://alsa-project.org/db/?
f=252f92c7a1df3c755d16ee69353b26d2535a4d81

I have tested the kernel 5.8-rc1 but it does not make any difference.

Let me know if I can do anything else to test the issue.