Problem summary

• Only one sound output device is shown, which outputs to the speakers and headphones simultaneously.
  • That is, there's only one port in Pavucontrol, and only one line in pactl list | grep 'Active Port.*output.*'.
• It is therefore impossible to mute the speakers while listening on headphones.
• The two outputs work correctly in Windows.

I would be incredibly grateful if anyone could help me figure this one out, because I'm stumped and not finding anything that helps.

System

• Hardware: Lenovo Thinkpad E495
  • Updated to latest firmware/BIOS.
  • No newer drivers available from manufacturer.
• Ubuntu 21.04
  • Kubuntu variant
  • Kernel 5.11
• Freshly installed; updated with apt update; apt upgrade but no other software installed.

What I've tried so far

Uninstalling linux-sound-base, alsa-base, and alsa-utils, and installing them fresh.

Looking at the devices in AlsaMixer; Master, PCM, Mic Boost, and Beep are the devices visible. Master controls both speakers and headphones.

Editing /etc/modprobe.d/alsa-base.conf to add

alias snd-card-0 snd-hda-intel
alias sound-slot-0 snd-hda-intel
options snd-hda-intel model=thinkpad

Trying that again with model=auto probe_mask=1.

Removing and re-inserting the headphones between each of the above things.

Possibly relevant information

Output of alsactl restore

alsactl: load_state:1683: Cannot open /var/lib/alsa/asound.state for reading: No such file or directory
alsa-lib parser.c:260:(error_node) UCM is not supported for this HDA model (HD-Audio Generic at 0xd06c8000 irq 79)
alsa-lib main.c:1014:(snd_use_case_mgr_open) error: failed to import hw:0 use case configuration -6
Found hardware: "HDA-Intel" "ATI R6xx HDMI" "HDA:1002aa01,00aa0100,00100700" "0x17aa" "0x5124"
Hardware is initialized using a generic method
alsa-lib parser.c:260:(error_node) UCM is not supported for this HDA model (HD-Audio Generic at 0xd06c0000 irq 80)
alsa-lib main.c:1014:(snd_use_case_mgr_open) error: failed to import hw:1 use case configuration -6
Found hardware: "HDA-Intel" "Conexant CX8070" "HDA:14f11f86,17aa5124,00100100" "0x17aa" "0x5124"
Hardware is initialized using a generic method

Output of dmesg | grep -i "snd|firmware"

ACPI: [Firmware Bug]: BIOS _OSI(Linux) query ignored
acpi PNP0A08:00: [Firmware Info]: MMCONFIG for domain 0000 [bus 00-3f] only partially covers this bridge
tpm tpm0: [Firmware Bug]: TPM interrupt not working, polling instead
[drm] Found VCN firmware Version ENC: 1.12 DEC: 2 VEP: 0 Revision: 5
[drm] PSP loading VCN firmware
snd_pci_acp3x 0000:05:00.5: enabling device (0000 -> 0002)
snd_pci_acp3x 0000:05:00.5: ACP audio mode : 2
Bluetooth: hci0: RTL: assuming no firmware upload needed
snd_hda_intel 0000:05:00.1: enabling device (0000 -> 0002)
snd_hda_intel 0000:05:00.1: Handle vga_switcheroo audio client
snd_hda_intel 0000:05:00.6: enabling device (0000 -> 0002)
snd_hda_intel 0000:05:00.1: bound 0000:05:00.0 (ops amdgpu_dm_audio_component_bind_ops [amdgpu])
snd_hda_codec_conexant hdaudioC1D0: CX8070: BIOS auto-probing.
snd_hda_codec_conexant hdaudioC1D0: autoconfig for CX8070: line_outs=1 (0x17/0x0/0x0/0x0/0x0) type:speaker
snd_hda_codec_conexant hdaudioC1D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
snd_hda_codec_conexant hdaudioC1D0:    hp_outs=0 (0x0/0x0/0x0/0x0/0x0)
snd_hda_codec_conexant hdaudioC1D0:    mono: mono_out=0x0
snd_hda_codec_conexant hdaudioC1D0:    inputs:
snd_hda_codec_conexant hdaudioC1D0:      Internal Mic=0x1a
snd_hda_codec_conexant hdaudioC1D0:      Mic=0x19
rtw_8822be 0000:04:00.0: Firmware version 27.2.0, H2C version 13
psmouse serio2: trackpoint: Elan TrackPoint firmware: 0x11, buttons: 3/3
rtw_8822be 0000:04:00.0: firmware failed to leave lps state
rtw_8822be 0000:04:00.0: firmware failed to leave lps state
rtw_8822be 0000:04:00.0: firmware failed to leave lps state
rtw_8822be 0000:04:00.0: firmware failed to leave lps state
snd_pci_acp3x 0000:05:00.5: ACP audio mode : 2
snd_pci_acp3x 0000:05:00.5: ACP audio mode : 2
snd_pci_acp3x 0000:05:00.5: ACP audio mode : 2
snd_pci_acp3x 0000:05:00.5: ACP audio mode : 2

Output of aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: Generic [HD-Audio Generic], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Generic [HD-Audio Generic], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Generic [HD-Audio Generic], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Generic_1 [HD-Audio Generic], device 0: CX8070 Analog [CX8070 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0