[BUG] Acer Swift SFG16-I71 Panther Lake – RT712 headphones detected but silent, RT712 L3 + RT1320 L1

[VicPop]

Describe the bug

The internal 3.5 mm headphone output on an Acer Swift SFG16-I71
(Panther Lake, Intel Core Ultra X9 388H) is detected correctly under
Linux, but produces no audio.

Internal speakers and the internal SoundWire microphone work correctly.

When headphones are inserted:

• The jack insertion is detected.
• A "Headphones" output appears in the desktop audio settings.
• The headphones can be selected as the default output.
• Playback streams are routed to the headphone sink.
• ALSA exposes the Jack Out PCM.
• The Headphone mixer switch is enabled.
• However, the physical headphones remain completely silent.

Direct ALSA playback to the headphone PCM is also silent, so the issue
does not appear to be caused by PipeWire or WirePlumber.

Hardware

Laptop:
Acer Swift SFG16-I71

CPU:
Intel Core Ultra X9 388H (Panther Lake)

GPU:
Intel Arc B390

BIOS:
V1.05

SoundWire devices detected:

link 1:
mfg_id 0x025d
part_id 0x1320
version 0x3

link 3:
mfg_id 0x025d
part_id 0x0712
version 0x3

/sys/bus/soundwire/devices contains:

sdw:0:1:025d:1320:01
sdw:0:3:025d:0712:01
sdw-master-0-1
sdw-master-0-3

RT712 uevent:

DEVTYPE=sdw_slave
DRIVER=rt712-sdca
MODALIAS=sdw:m025Dp0712v03c01

The RT712 device is therefore binding to the rt712-sdca driver.

Software

Distribution:
Fedora Rawhide / Fedora 46

Tested kernels include:

6.19.10-300.fc44.x86_64
7.2.2-300.fc44.x86_64
7.3.0-0.rc2.260911g08df884136f1.29.fc46.x86_64

SOF firmware was installed and updated from the Fedora repositories.

Behaviour on different kernels

Kernel 6.19.10:
Internal speakers/microphone did not work correctly.

Kernel 7.2.2:
Internal speakers started working.
Internal SoundWire microphone started working.
3.5 mm headphone jack is detected, but headphones remain silent.

Kernel 7.3:
Internal speakers continue to work.
Headphone jack continues to be detected.
Headphones remain completely silent.

Kernel messages / machine selection

During a normal boot the system reports:

"No SoundWire machine driver found for the ACPI-reported configurations"

and then:

"Use SoundWire default machine driver with function topologies"

The generic function topology files loaded include:

sof-sdca-1amp-id2.tplg
sof-sdca-jack-id0.tplg
sof-sdca-mic-id4.tplg

The physical SoundWire configuration appears to be:

RT712 on link 3
RT1320 on link 1

Possible missing Panther Lake machine configuration

I noticed that current Linux Panther Lake ACPI machine matching contains
configurations for combinations including:

RT712 L2 + RT1320 L1
RT712 L3 + RT1320 L2
RT712 L3 + RT1320 L3

but I could not find an RT712 L3 + RT1320 L1 machine definition.

Likewise, the installed SOF topology set contains files such as:

sof-ptl-rt712-l2-rt1320-l1.tplg
sof-ptl-rt712-l3-rt1320-l2.tplg
sof-ptl-rt712-l3-rt1320-l3.tplg

but no:

sof-ptl-rt712-l3-rt1320-l1.tplg

This appears to match the physical configuration reported by this
machine (RT712 link 3 + RT1320 link 1).

I am not certain that this is the cause of the silent analogue
headphone output, but I wanted to highlight the mismatch.

Direct ALSA test

The headphone PCM exists:

card 0: sof-soundwire

device 0:
Jack Out

Direct playback was tested with:

speaker-test -D hw:0,0 -c 2 -r 48000 -F S16_LE -t sine

speaker-test successfully opens the PCM and reports:

Front Left
Front Right

but nothing can be heard through the headphones.

This bypasses PipeWire/WirePlumber and the headphones are still silent.

Mixer observations

amixer shows the Headphone switch enabled.

The RT712 controls are visible.

Testing the relevant RT712 output switches did not produce headphone
audio.

Internal speakers continue to operate normally.

Other audio outputs

Internal speakers: WORKING
Internal SoundWire microphone: WORKING
HDMI audio: WORKING
USB-C HDMI audio: WORKING
3.5 mm jack detection: WORKING
3.5 mm headphone audio: NOT WORKING

Reproduction

1. Boot Fedora on Acer Swift SFG16-I71.
2. Insert known-working wired headphones into the 3.5 mm jack.
3. Fedora detects the insertion and exposes a Headphones output.
4. Select Headphones as the output.
5. Play audio or use the GNOME speaker test.
6. No audio is produced by the headphones.
7. Direct ALSA playback to hw:0,0 is also silent.

Reproduction rate:
100%

Expected behaviour

When headphones are inserted and the Headphones output is selected,
audio should be produced through the 3.5 mm headphone jack.

Additional observation

The RT712 codec is successfully enumerated and bound to rt712-sdca, and
jack detection works. This seems to indicate that the SoundWire digital
communication with the codec is functional.

The failure appears specifically related to the analogue headphone
playback path / machine configuration / topology.

Could the missing Panther Lake RT712-L3 + RT1320-L1 machine/topology
combination be responsible for this Acer model?

If additional alsa-info, dmesg, topology, ACPI, SoundWire, or codec
register information is needed, I can provide it.