Internal microphone non-functional on Dell XPS 16 9640 — SOF topology ABI mismatch

[Zormaster]

Hardware: Dell XPS 16 9640
CPU: Intel Meteor Lake
Audio codec: Cirrus Logic cs42l43 + cs35l56 (SoundWire)
OS: Pop!_OS 24.04
Kernel: 6.18.7-76061807-generic (also tested 6.14-oem and 6.17-oem)

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Problem

The internal microphone produces no audio input. All capture devices return silence. The root cause is a mismatch between the SOF topology ABI version shipped in firmware-sof-signed and the SOF Kernel ABI in all available Pop!_OS kernels:

sof-audio-pci-intel-mtl 0000:00:1f.3: Topology: ABI 3:29:1 Kernel ABI 3:23:1

The topology files require Kernel ABI 3:29, but every available kernel (including OEM variants 6.14 and 6.17) only supports Kernel ABI 3:23. As a result the SOF DSP mic pipeline never initializes and all capture returns silence.

What I've tried

• Switching to pro-audio PipeWire profile (fixes speakers, not mic)
• Installing linux-oem-24.04, linux-oem-6.14, linux-oem-6.17 — all show Kernel ABI 3:23
• Manually installing firmware-sof-signed 2025.05.1-1build1 from Ubuntu — topology files still require ABI 3:29
• Manual ALSA mixer manipulation of cs42l43 decimator/PDM controls — no effect since the DSP pipeline isn't initialized

Upstream status

This is a known issue tracked at:

• Ubuntu Launchpad: https://bugs.launchpad.net/ubuntu/+source/firmware-sof/+bug/2069760 — marked Fix Released for Noble
• SOF upstream: [BUG] Internal microphone never works on new ASUS Zenbook S 14 UX5406SA Lunar Lake cs42l43 thesofproject/sof#9834

The Ubuntu fix requires the 6.10-oem kernel which carries the kernel-side SOF ABI 3:29 support. Pop!_OS does not currently carry this kernel or an equivalent with the SOF ABI bump.

Request

Please sync or backport the kernel SOF ABI fix so that the topology files in firmware-sof-signed can load correctly on Meteor Lake hardware. This affects all Dell XPS 16 9640 users (and likely other cs42l43-based laptops) on Pop!_OS.