After extensive debugging, the issue has been isolated to incorrect ALSA mixer control mapping.

Technical Details

Hardware Configuration:

- Laptop Model: ASUS ROG Zephyrus G14 (GA403W) - Audio Codec: Realtek ALC285 (Subsystem ID: 0x10431024) - Amplifiers: Dual Cirrus Logic CS35L56 smart amplifiers - ALSA Card: Card 2 (HD-Audio Generic) - Driver: snd_hda_intel with cs35l56-hda module

Amplifier Status: The CS35L56 amplifiers are being detected and initialized correctly:

cs35l56-hda i2c-CSC3556:00-cs35l56-hda.0: DSP1: Firmware: 1a00d6 vendor: 0x2 v3.11.16

cs35l56-hda i2c-CSC3556:00-cs35l56-hda.1: DSP1: Firmware: 1a00d6 vendor: 0x2 v3.11.16

Firmware files loaded:

- cirrus/cs35l56-b0-dsp1-misc-10431024-spkid1.wmfw - cirrus/cs35l56-b0-dsp1-misc-10431024-spkid1-amp1.bin - cirrus/cs35l56-b0-dsp1-misc-10431024-spkid1-amp2.bin

The Actual Problem

Current (broken) behavior:

- The volume slider controls Master Playback Volume (numid=24) on the ALC285 codec - This control only affects the analog signal level going into the CS35L56 amplifiers - Lowering this control degrades signal quality (adds muffling/distortion) without actually reducing speaker output volume - The CS35L56 amplifiers remain at a fixed gain, so perceived loudness doesn't change significantly

Correct behavior should be:

- The volume slider should control AMP1 Speaker Playback Volume (numid=6) and AMP2 Speaker Playback Volume (numid=12) - The codec's Master and Speaker controls should remain at 100% for optimal signal-to-noise ratio

Verified working configuration:

bash

# Codec output (should be fixed at these values)

amixer -c2 sset

'Master'

100

%

amixer -c2 sset

'Speaker'

100

%

# Amplifier controls (should be user-adjustable via volume slider)

amixer -c2 sset

'AMP1 Speaker'

85

%

amixer -c2 sset

'AMP2 Speaker'

85

%

``

`

Manual testing confirms:

- ✅

`

AMP1 Speaker

`

and

`

AMP2 Speaker

`

controls properly adjust speaker loudness

- ✅ Volume range

0

-100% works without distortion when codec is at

100

%

- ❌ PipeWire/desktop environment uses the wrong mixer controls

### PipeWire Configuration

Current sink properties show it's using ACP

(

ALSA Card Profiles

)

:

`

`

`

api.alsa.use-acp

=

"true"

api.alsa.path

=

"front:2"

`

`

`

The automatically selected mixer path is choosing

`

Master

`

as the primary volume control instead of the CS35L56 amp controls.

### Required Fix

This needs one of the following solutions:

1

. **ALSA UCM

(

Use Case Manager

)

profile**

for

device ID

`

10431024

`

:

- Lock codec controls at

100

%

- Expose AMP1/AMP2 Speaker controls as primary volume

2

. **Custom ALSA mixer path** at

`

/usr/share/alsa/mixer/paths/

`

:

- Define AMP1/AMP2 Speaker as volume elements

- Set Master/Speaker to

`

volume

=

ignore

`

or

`

volume-limit

=

0.0

`

3

. **Kernel quirk**

in

`

sound/pci/hda/patch_realtek.c

`

:

- Add model-specific configuration

for

GA403W

- Similar to how other ASUS models with CS35L41/CS35L56 are handled

4

. **PipeWire/WirePlumber profile update**:

- Device-specific configuration to use correct mixer elements

### Relevant Files

**ALSA Controls Output:**

`

``

numid

=

6

,iface

=

MIXER,name

=

'AMP1 Speaker Playback Volume'

:

values

=

400

|

dBscale-min

=

-100.00dB,step

=

0

.25dB,mute

=

0

|

Range:

0

-448

numid

=

12

,iface

=

MIXER,name

=

'AMP2 Speaker Playback Volume'

:

values

=

400

|

dBscale-min

=

-100.00dB,step

=

0

.25dB,mute

=

0

|

Range:

0

-448

numid

=

24

,iface

=

MIXER,name

=

'Master Playback Volume'

:

values

=

39

|

dBscale-min

=

-65.25dB,step

=

0

.75dB,mute

=

0

|

Range:

0

-87

Codec Information:

- See full codec dump at: https://paste.centos.org/view/6c3a3640 - Full diagnostics at: https://paste.centos.org/view/c0d20bf3

Temporary Workaround

Users can manually set correct levels on boot with this autostart script:

~/.config/autostart/audio-fix.desktop:

desktop

[Desktop Entry]

Type=Application

Name=Audio Fix

Exec=/usr/bin/bash -c "sleep 5 && amixer -c2 sset 'Master' 100%% && amixer -c2 sset 'Speaker' 100%% && amixer -c2 sset 'AMP1 Speaker' 85%% && amixer -c2 sset 'AMP2 Speaker' 85%%"

Hidden=false

NoDisplay=false

However, the volume slider will still not function correctly.

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