Public bug reported:
After upgrading from Ubuntu 24.04 to Ubuntu 26.04 on a MacPro6,1 (Late
2013), the built-in speaker no longer works correctly.
The machine uses a Cirrus Logic CS4208 codec with subsystem ID
`106b:7800`. External speakers connected through the 3.5 mm audio jack
continue to work normally.
The built-in speaker can be restored manually, but changing the volume
through the Ubuntu UI causes it to become silent again.
While the speaker is silent, the CS4208 speaker DAC at HDA node `0x03`
reports its amplifier values as:
```text
0xdf
0xe0
```
Both values have the HDA mute bit (`0x80`) set.
Manually clearing the mute bit with `hda-verb`:
```bash
sudo hda-verb /dev/snd/hwC0D0 0x03 SET_AMP_GAIN_MUTE 0x905f
sudo hda-verb /dev/snd/hwC0D0 0x03 SET_AMP_GAIN_MUTE 0xa060
```
immediately restores audio from the built-in speaker.
The following also appears correct while the issue occurs:
```text
Codec: Cirrus Logic CS4208
Subsystem Id: 0x106b7800
GPIO mask = 0x1
GPIO direction = 0x1
GPIO data = 0x1
Speaker pin 0x12 widget control = 0x40
Headphone pin 0x10 sense = 0x0
```
The kernel also detects the MacPro6,1-specific codec fixup:
```text
snd_hda_codec_cs420x hdaudioC0D0: CS4208: picked fixup for codec SSID 106b:7800
```
So the speaker amplifier appears to be enabled, the speaker pin is
configured as an output, and no headphones are falsely detected.
The issue is reproducible as follows:
1. Select the built-in speaker as the output.
2. Manually restore/unmute the speaker; audio works.
3. Change the volume using the Ubuntu desktop volume control.
4. The built-in speaker becomes silent.
5. Node `0x03` has its hardware mute bit set again.
6. Clearing the mute bit with `hda-verb` restores audio immediately.
This worked normally before upgrading from Ubuntu 24.04.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-30-generic 7.0.0-30.30
ProcVersionSignature: Ubuntu 7.0.0-30.30-generic 7.0.12
Uname: Linux 7.0.0-30-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sat Aug 22 19:52:21 2026
InstallationDate: Installed on 2025-12-09 (256 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
IwDevWlp13s0Link:
Error: command ['iw', 'dev', 'wlp13s0', 'link'] failed with exit code 255:
command failed: Operation not permitted (-1)
Connected to <hidden-mac> (on wlp13s0)
SSID: <hidden>
freq: 5180.0
MachineType: Apple Inc. MacPro6,1
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-30-generic
root=UUID=2a237b86-6045-4c2a-8e5d-41bbcfabb336 ro radeon.si_support=0
amdgpu.si_support=1 amdgpu.dc=1 intel_iommu=off amdgpu.dpm=0
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: Upgraded to resolute on 2026-08-01 (21 days ago)
dmi.bios.date: 10/07/2023
dmi.bios.release: 0.1
dmi.bios.vendor: Apple Inc.
dmi.bios.version: 481.0.0.0.0
dmi.board.name: Mac-F60DEB81FF30ACF6
dmi.board.vendor: Apple Inc.
dmi.board.version: MacPro6,1
dmi.chassis.type: 2
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F60DEB81FF30ACF6
dmi.modalias:
dmi:bvnAppleInc.:bvr481.0.0.0.0:bd10/07/2023:br0.1:svnAppleInc.:pnMacPro6,1:pvr1.0:rvnAppleInc.:rnMac-F60DEB81FF30ACF6:rvrMacPro6,1:cvnAppleInc.:ct2:cvrMac-F60DEB81FF30ACF6:sku:pfaMacPro:
dmi.product.family: MacPro
dmi.product.name: MacPro6,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2164824
Title:
MacPro6,1 CS4208 internal speaker DAC becomes muted when changing
volume
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