No sound in Ubuntu 18.04 after rebooting from windows 10 [closed]

I'm on 18.04 in a Asus Zenbook laptop and my sound works fine after a shutdown (clean slate). If I boot into ubuntu, sound works, if i reboot still into ubuntu, sound still works. If I boot into Windows 10 and then shut down and boot into ubuntu, sound works. But if I boot into windows 10 and then reboot into ubuntu, now the sound doesn't work (nothing is muted in alsamixer but there is no sound at all). Only a shutdown fixes it, reboots don't. I already disabled fast boot in windows and killed/cleaned pulse audio as suggested in all these other answers. Sound doesn't work on headphones either

I took two syslog snapshots when sound works and when it doesn't and I don't see any significant differences between them. It really looks to me like a hardware/firmware issue but I imagine there must be a way to fix it from software. Any suggestions?

hilikus@developorium:~$ grep -C 3 snd no-sound-after-reboot  
May  5  developorium kernel: [    3.229033] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
May  5  developorium kernel: [    3.232083] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2
May  5  developorium kernel: [    3.232086] cfg80211: failed to load regulatory.db
May  5  developorium kernel: [    3.235334] snd_hda_intel 0000:00:1f.3: enabling device (0000 -> 0002)
May  5  developorium kernel: [    3.235547] uvcvideo: Found UVC 1.00 device USB2.0 HD UVC WebCam (13d3:5694)
May  5  developorium kernel: [    3.244124] uvcvideo 1-6:1.0: Entity type for entity Realtek Extended Controls Unit was not initialized!
May  5  developorium kernel: [    3.244126] uvcvideo 1-6:1.0: Entity type for entity Extension 4 was not initialized!
--
May  5  developorium kernel: [    3.416112] thermal thermal_zone6: failed to read out thermal zone (-61)
May  5  developorium kernel: [    3.417112] iwlwifi 0000:02:00.0 wlp2s0: renamed from wlan0
May  5  developorium kernel: [    3.804303] [drm] RC6 on
May  5  developorium kernel: [    3.832374] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
May  5  developorium kernel: [    3.861595] snd_hda_codec_realtek hdaudioC0D0: autoconfig for ALC294: line_outs=1 (0x17/0x0/0x0/0x0/0x0) type:speaker
May  5  developorium kernel: [    3.861597] snd_hda_codec_realtek hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
May  5  developorium kernel: [    3.861598] snd_hda_codec_realtek hdaudioC0D0:    hp_outs=1 (0x21/0x0/0x0/0x0/0x0)
May  5  developorium kernel: [    3.861599] snd_hda_codec_realtek hdaudioC0D0:    mono: mono_out=0x0
May  5  developorium kernel: [    3.861600] snd_hda_codec_realtek hdaudioC0D0:    inputs:
May  5  developorium kernel: [    3.861601] snd_hda_codec_realtek hdaudioC0D0:      Mic=0x12
May  5  developorium kernel: [    3.915132] input: HDA Intel PCH Headphone as /devices/pci0000:00/0000:00:1f.3/sound/card0/input11
May  5  developorium kernel: [    3.915169] input: HDA Intel PCH HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:1f.3/sound/card0/input12
May  5  developorium kernel: [    3.915200] input: HDA Intel PCH HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:1f.3/sound/card0/input13

This ended up being a bug in the Realtek ALC294 alsa driver. It has been already reported in launchpad: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1742852

Upvote it if it affects you so that devs increase its priority

Windows is notorious for shutting off devices when rebooting and then powering them back on after rebooting. This is particularly problematic with Network cards but as your question illustrates it happens with sound cards as well.

From this Dell forum other users suffer the same fate. As stated you you can:

• reboot into Windows 10
• select shutdown
• cold boot your system with power button
• select Ubuntu

You can save time by suspending and resuming your Ubuntu 16.04 as one of the answer in this thread describes.

Summary

You can't reboot Windows and select Ubuntu from Grub menu. You have to shutdown and hit power button as per the links above. You could visit the Dell links and post a request for a Linux utility to power on the device.

The best solution may be to post a Windows question in Super User asking how to change Windows not to power off sound card during reboot.