Public bug reported:
On a Dell Precision 5690 (Ubuntu-certified; Core Ultra 7 165H Meteor
Lake, BIOS 1.23.0, Ubuntu 24.04, kernel 6.14.0-37-generic, sof-soundwire
audio with Realtek RT713/RT1713 codecs), the hardware mic-mute key and
the desktop's software mute can become inverted, after which the
internal microphone captures pure zeros in every visible mute state and
appears permanently dead. This has driven users of this machine to
disable the microphone in BIOS (see
https://github.com/thesofproject/sof/issues/9852). All findings below
were established by systematic experiment.
How mute works on this machine (verified):
* The mic-mute hotkey is handled by the EC: it toggles the hardware mic mute
and the physical keyboard LED directly, and separately emits a key event
(dell-privacy WMI) that the desktop handles by toggling software mute. When the
OS is awake, one keypress therefore toggles both sides and they stay consistent.
* The software mute chain works correctly: PipeWire mute drives the ALSA
control "rt713-dmic FU1E Capture Switch" via UCM (verified with amixer while
toggling).
* /sys/.../dell_privacy_current_state accurately tracks the EC hardware mute
state (verified against the physical LED).
Bug 1 — the kernel LED device is a dead stub:
/sys/class/leds/dell-privacy::micmute neither controls nor reflects the
physical LED on this model. Writing 1/0 to brightness does not change the
physical LED; when the physical LED is ON (EC-muted), brightness still reads 0.
Consequently the snd-ctl-led "follow-mute" mechanism cannot possibly sync the
LED here: manually attaching the capture switch (echo "numid=..." >
/sys/class/sound/ctl-led/mic/card1/attach) makes the *kernel LED device* follow
software mute, but the physical LED remains dark (verified).
Bug 2 — consequence: no sync channel between hardware and software mute:
Two reliable ways to invert the states:
a) Mute the mic in the desktop audio applet (software-only; EC/LED
unaffected), then press the hardware mute key.
b) Press the mute key while the system is suspended: the EC toggles (LED
changes), but the OS never receives the key event.
Once inverted, the hotkey preserves the inversion (it toggles both sides
together), so at least one of the two mutes is always engaged: the microphone
captures 100% zero samples regardless of the visible LED/applet state. To a
user this is indistinguishable from dead hardware. Recovery requires realizing
that the applet (software-only) toggle must be used to re-align the states —
nothing in any UI indicates the mismatch.
Expected behavior: hardware and software mute state stay consistent (as
on Windows on the same machine), e.g. by the kernel reflecting EC mute-
state changes to userspace (input switch events or a functional
LED/state device that PipeWire/desktops can follow).
Userspace workaround (works, running here): a 1-second poller that
mirrors EC state changes into PipeWire mute:
STATE=$(ls
/sys/devices/platform/*/wmi_bus/*/6932965F-1671-4CEB-B988-D3AB0A901919/dell_privacy_current_state)
read_ec() { grep -q "\[Microphone\] \[muted\]" "$STATE" && echo muted || echo
unmuted; }
LAST=$(read_ec)
while sleep 1; do CUR=$(read_ec); [ "$CUR" != "$LAST" ] || continue
ID=$(wpctl status | grep "SoundWire microphones" | grep -oE "[0-9]+" | head
-1)
[ "$CUR" = muted ] && wpctl set-mute "$ID" 1 || wpctl set-mute "$ID" 0;
LAST=$CUR; done
Related: an unrelated capture-corruption issue on the same machine is
tracked at LP#2160386 /
https://github.com/thesofproject/sof/issues/10988 (full-scale impulse-
train corruption — distinct symptom, not mute-related). Closest prior
report of the LED half of this bug appears to be LP#1965846 (XPS 9315
mic-mute LED).
Happy to test patches; the inversion reproduces on demand.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.14.0-37-generic 6.14.0-37.37~24.04.1
ProcVersionSignature: Ubuntu 6.14.0-37.37~24.04.1-generic 6.14.11
Uname: Linux 6.14.0-37-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Sat Jul 11 00:21:12 2026
InstallationDate: Installed on 2024-10-22 (626 days ago)
InstallationMedia: Kubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240425.1)
MachineType: Dell Inc. Precision 5690
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.14.0-37-generic
root=UUID=f06237b6-ac5a-48e0-a5ae-74a6c81d5872 ro quiet splash
nvidia.NVreg_PreserveVideoMemoryAllocations=1 vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.14.0-37-generic N/A
linux-backports-modules-6.14.0-37-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.14
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/23/2026
dmi.bios.release: 1.23
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.23.0
dmi.board.name: 088TDK
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.24
dmi.modalias:
dmi:bvnDellInc.:bvr1.23.0:bd04/23/2026:br1.23:efr1.24:svnDellInc.:pnPrecision5690:pvr:rvnDellInc.:rn088TDK:rvrA00:cvnDellInc.:ct10:cvr:sku0CC8:
dmi.product.family: Precision
dmi.product.name: Precision 5690
dmi.product.sku: 0CC8
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-6.14 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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https://bugs.launchpad.net/bugs/2160389
Title:
Dell Precision 5690: dell-privacy::micmute LED is nonfunctional;
hardware/software mic-mute states can invert into a "microphone
permanently dead" deadlock
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