ThinkPad X1 Carbon Gen 13 (21NT, LNL, rt713-sdca + rt1318): headphone jack detected but no audio output; works on Windows #5980

Hardware

• Lenovo ThinkPad X1 Carbon Gen 13, MTM 21NTCTO1WW
• BIOS: N4BET77W (1.47)
• Platform: Intel Lunar Lake-M HD Audio Controller [8086:a828], subsystem 17aa:2339
• SoundWire codecs: rt713-sdca (headset, link 0) + rt1318 (speaker amp, link 1)
• Card components: hs:rt713-sdca spk:rt1318 mic:dmic cfg-mics:2
• Topology: intel/sof-ipc4-tplg/sof-lnl-rt713-l0-rt1318-l1-2ch.tplg
• Codec driver in use: snd_soc_rt712_sdca

Problem

The 3.5 mm headphone jack is detected correctly, but no audio is produced.
Internal speakers (rt1318) work normally. The same headphones work on
this machine under Windows 11 (dual boot) and on other devices.

Software tested (all fail identically)

Observed state with headphones plugged in

• Headphone Jack (CARD) = on: plug detection works
• Headphone Switch = on
• rt713 FU05 Playback = 87/87 (0 dB), switch on
• Pre Mixer Jack Out / Post Mixer Jack Out / Pre Mixer Deepbuffer Jack Out = 45/45 (0 dB)
• PipeWire: Headphones sink is default and the stream is [active]
• No rt713 / sdw / sof errors in the kernel log
• Headset Mic Jack = off (3-pole headphones)

Tests performed

1. Playback via PipeWire to the Headphones sink: silent
2. Raw ALSA with PipeWire stopped:
   speaker-test -D plughw:0,0 -c 2 -t wav (Jack Out) → silent
   speaker-test -D plughw:0,31 -c 2 -t wav (Deepbuffer Jack Out) → silent
3. Speakers via plughw:0,2 / Speaker sink → works
4. Play audio through headphones in Windows (working), then warm reboot
   directly into Linux → still silent (Linux init appears to put the
   codec's headphone path into a non-working state, not just fail to enable it)
5. Cold boot, Windows Fast Startup / hibernation disabled → silent
6. BIOS and fwupd updates applied → silent

alsa-info

• Ubuntu 26.04.1 / kernel 7.0.0-38: <<ALSA_INFO_URL_26.04>>
• Ubuntu 24.04.4 / kernel 6.17.0-1033-oem: https://alsa-project.org/db/?f=fcee9162e76ce3bba0e1971ba7783ca943f92689

Possibly related

<> On Ubuntu 26.04.1 no capture sources appear in PipeWire
(internal DMIC / headset mic missing), although they appeared on 24.04.

Happy to test patches, kernel builds, or provide register dumps / dynamic debug output.