I've the same problem on Lenovo Yoga c930.
In soud config it says Dummy output. Similar problem with mic.
This all from yesterday.
Please help!!!

If you're using > 5.3.0-40 kernels, this might work for you:

Add "options snd-hda-intel dmic_detect=0" in the /etc/modprobe.d/alsa-base.conf.

After adding the line to the config file I rebooted my laptop and now it works.

More details about this bug can be found on mail-archive (search for 1864061 - this is the ID of the bug - sorry I can't post links yet).

Hope it helps.

Ok, this solved the problem with the audio .... THANKS, but not with the microphone !!!!

Ah sorry, I haven't checked the mic...

I guess the only viable solution is to revert back to using an older kernel until it's properly fixed. :/

Thanks a lot neaterpeter, speaker problem solved. Microphone has never worked on my c940 and is still not working. I can live with that for now and wait for a proper fix.

Hi!
Got the same issue on

Lenovo YOGA C930

[INDENT]Linux Mint 19.3 / Ubuntu 18.04/INDENT]
Only got this issue since a couple of days.
I can only assume that some update around 17.03.2020 is responsible for that.

Tried above options with no change.
Also tried other solutions no change.
Any input is welcome.
Thank you in advance.

Here is some data:
➜ ~ uname -r
5.3.0-42-generic

➜ ~ lspci -nnk | grep -A2 Audio
00:1f.3 Multimedia audio controller [0401]: Intel Corporation Sunrise Point-LP HD Audio [8086:9d71] (rev 21)
Subsystem: Lenovo Sunrise Point-LP HD Audio [17aa:3831]
Kernel driver in use: snd_soc_skl
Kernel modules: snd_hda_intel, snd_soc_skl

➜ ~ sudo dmesg | grep -i audio
[ 0.103742] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[ 3.714632] snd_soc_skl 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
[ 3.957703] HDMI HDA Codec ehdaudio0D2: Max dais supported: 3
[ 214.794189] Modules linked in: rfcomm xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo xt_addrtype iptable_filter iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 bpfilter br_netfilter bridge stp llc ccm hid_sensor_als hid_sensor_accel_3d hid_sensor_trigger industrialio_triggered_buffer kfifo_buf hid_sensor_iio_common industrialio hid_sensor_custom 8250_dw hid_sensor_hub snd_soc_dmic aufs wacom hid_multitouch snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_soc_skl(-) snd_soc_hdac_hda snd_hda_ext_core snd_soc_skl_ipc snd_soc_sst_ipc overlay snd_soc_sst_dsp bnep snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_intel mei_hdcp kvm_intel snd_intel_nhlt intel_rapl_msr snd_hda_codec kvm snd_hda_core irqbypass snd_hwdep snd_pcm iwlmvm snd_seq_midi crct10dif_pclmul nls_iso8859_1 snd_seq_midi_event crc32_pclmul ghash_clmulni_intel mac80211
[ 215.890790] snd_soc_skl 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
[ 215.902992] HDMI HDA Codec ehdaudio0D2: Max dais supported: 3

Too many first-time-poster-single-post members in this thread. A weird SEO glitch or something more sinister?
I'm keeping an eye on this. Sometimes they come back and edit spam links in.

Hello!
I hereby confirm I'm a real human being
With the same Dummmy Output.

It's just that people with a similar Linux distro, receiving similar updates on similar hardware.. get, unsuprisingly similar results.
So they follow the same pattern:
* Search for other having same problem
* Checking described solution
* Once options run out, they try to write for help.
* Not doing this on a regular basis (because they don't just mess for fun with their soundcards ) they create accounts on such forums.
* and the beat goes on..

Finally, I've also reverted back to 5.3.0-40 kernel and got back the sound.
All the best!

I had the "dummy output" problem on Ubuntu 18.04. used the following command to reboot the audio system and it worked

pulseaudio -k && sudo alsa force-reload

thanks dude!