Public bug reported:
## Summary
On the HP EliteBook X G2a (14", "Next Gen AI PC" line, AMD Strix
Point/Halo, ACP 7.0), the AMD ACP70 audio machine driver fails to bind
at all:
```
platform acp_asoc_acp70.0: warning: No matching ASoC machine driver found
```
Only the separate HDMI/DP audio device (`snd_hda_intel`) works; there is
no ALSA card for the built-in speakers, microphone, or SoundWire-
attached audio at all. `/proc/asound/cards` shows only the HDMI "HD-
Audio Generic" card.
Root cause, confirmed by decompiling the machine's own ACPI tables: the
BIOS-supplied `SSDT` (OEM Table ID `OEMACP`, matching AMD's shared ACP70
reference SSDT template used across OEMs) sets:
```asl
Package (0x02)
{
"acp-audio-config-flag",
0x10
}
```
This is the *same* property and *same* disabling value (`0x10`) reported
on the ASUS Zenbook S16 (UM5606GA) for the identical bug class — see
https://gist.github.com/trikko/11bef1a5c6d7f6cd2e7ef70603d7ba0d — where
changing it to `0x00` restored audio. On this HP board, the SoundWire
controller and endpoints (2 TAS-style amp-class speaker configs, DMIC
array, headset mic) are otherwise fully described in the same SSDT and
marked enabled (`"amd-sdw-enable"` = `One` on both SoundWire manager
instances), so the BIOS is describing complete, valid hardware — it is
only this one flag preventing Linux from bringing it up.
## System
- **Model**: HP EliteBook X G2a 14 inch Notebook Next Gen AI PC
- **Board**: `8EF5` (HP), Product family `103C_5336AN HP EliteBook`, SKU
`D72PQUT#ABA`
- **BIOS**: `Y88 Ver. 01.01.18`, 04/23/2026
- **CPU/APU**: AMD (Strix Point/Halo generation)
- **Audio controller**: `c3:00.5 Multimedia controller: AMD Audio Coprocessor
(rev 70)` — PCI `[1022:15e2]`, Subsystem `Hewlett-Packard Company Device 8ef5`
- **OS**: Ubuntu 26.04 LTS
- **Kernel**: `7.0.0-29-generic` (`CONFIG_ACPI_TABLE_UPGRADE=y`)
- Kernel driver bound to the ACP PCI device: `snd_acp_pci`
## Evidence
Kernel driver bind failure (`journalctl -k -b`):
```
platform acp_asoc_acp70.0: warning: No matching ASoC machine driver found
```
`/proc/asound/cards` (only HDMI present, no ACP70 card):
```
0 [Generic ]: HDA-Intel - HD-Audio Generic
HD-Audio Generic at 0xb45c0000 irq 152
```
`/sys/bus/soundwire/devices/` is empty — no SoundWire peripherals
enumerate (consistent with the machine driver never attaching to bring
the bus up).
Loaded modules include the full ACP70/SoundWire stack (`snd_acp70`,
`snd_sof_amd_acp70`, `snd_pci_ps`, `soundwire_amd`, `snd_soc_sdca`,
`snd_amd_sdw_acpi`), so this is not a missing-driver issue — the driver
is present but has nothing valid to bind to.
Relevant ACPI (`SSDT`, OEM ID `AMD`, OEM Table ID `OEMACP`, decompiled from
`/sys/firmware/acpi/tables/SSDT15` via `iasl -d`):
```
Device (ACP)
{
...
Device (SDWC) // SoundWire controller
{
Name (_ADR, 0x05)
...
"amd-sdw-enable", One
...
}
Device (SDWS) // audio config / endpoints (speaker amps, DMIC,
headset mic)
{
...
"acp-audio-config-flag", 0x10
"acp-audio-ep-type", ...
"acp-audio-ep-mic-array-geometry", ...
...
}
}
```
## What we tried
We attempted a userspace-only fix via the documented initrd ACPI table
override mechanism (`Documentation/admin-
guide/acpi/initrd_table_override.rst`): decompiled `SSDT15`, changed
`acp-audio-config-flag` from `0x10` to `0x00`, bumped the OEM Revision
(`0x00000001` → `0x00000002`), recompiled, and loaded it via
`GRUB_EARLY_INITRD_LINUX_CUSTOM`.
Every documented precondition checks out — correct cpio structure
(`kernel/firmware/acpi/*.aml`), uncompressed-then-compressed ordering,
correct OEM ID/OEM Table ID bytes (verified byte-identical to the
firmware original), `CONFIG_ACPI_TABLE_UPGRADE=y`, kernel lockdown is
`[none]`, normal (non-recovery) boot, override entry correctly present
in `grub.cfg` — but the override is not applied: post-reboot, the table
still shows OEM Revision `00000001` (unmodified) and the "No matching
ASoC machine driver found" warning persists. We could not identify why
the override is silently ignored on this kernel; this may be worth a
separate report if it reproduces on other systems, but we did not want
to conflate it with the primary issue here.
## Request
This looks like the same class of BIOS/DMI-quirk issue already being
actively patched for other AMD ACP70 laptops this generation (e.g. the
ASUS ProArt PX13 enablement work, and the open request for HP Omen 16
board `8D26` in CachyOS/linux-cachyos#705). Given HP's own ZBook 8 G2a
(same "G2a" generation) already has ACP70 machine-driver support
upstream (it received an LED-polarity quirk in 7.2-rc5, implying its
machine driver already matches), it seems plausible this EliteBook X G2a
(board `8EF5`) either needs:
- a machine-driver DMI/board quirk that ignores or overrides
`acp-audio-config-flag` for this board (mirroring whatever was done for the
PX13 and/or ZBook 8 G2a), or
- confirmation that this flag is intentional and Linux should honor a different
BIOS control path instead.
Happy to test patches — this machine is available for verification.
## References
- CachyOS/linux-cachyos#737 — ASUS ProArt PX13, same ACP70 platform, different
(SoundWire firmware/timing) root cause
- CachyOS/linux-cachyos#705 — HP Omen 16 (board 8D26), same "No matching ASoC
machine driver found" symptom, open
- CachyOS/linux-cachyos#853 — ASUS TUF Gaming A14, same symptom
- Hasun Park, "ASoC: amd: acp: PX13 ACP70 config and machine quirks" —
https://patchew.org/linux/[email protected]/
- ASUS Zenbook S16 (UM5606GA) — identical `acp-audio-config-flag` bug, same
`0x10` disabling value —
https://gist.github.com/trikko/11bef1a5c6d7f6cd2e7ef70603d7ba0d
- Linux 7.2-rc5 audio quirks (HP ZBook 8 G2a LED quirk) —
https://www.phoronix.com/news/Linux-7.2-rc5-Audio-Fixes
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-29-generic 7.0.0-29.29
ProcVersionSignature: Ubuntu 7.0.0-29.29-generic 7.0.12
Uname: Linux 7.0.0-29-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: mwhite 3238 F.... wireplumber
/dev/snd/seq: mwhite 3217 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Aug 6 19:40:07 2026
InstallationDate: Installed on 2026-08-05 (1 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: HP HP EliteBook X G2a 14 inch Notebook Next Gen AI PC
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=/vmlinuz-7.0.0-29-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/23/2026
dmi.bios.release: 1.18
dmi.bios.vendor: HP
dmi.bios.version: Y88 Ver. 01.01.18
dmi.board.name: 8EF5
dmi.board.vendor: HP
dmi.board.version: KBC Version 11.5C.00
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.ec.firmware.release: 17.92
dmi.modalias:
dmi:bvnHP:bvrY88Ver.01.01.18:bd04/23/2026:br1.18:efr17.92:svnHP:pnHPEliteBookXG2a14inchNotebookNextGenAIPC:pvrSBKPFV3:rvnHP:rn8EF5:rvrKBCVersion11.5C.00:cvnHP:ct10:cvr:skuD72PQUT#ABA:pfa103C_5336ANHPEliteBook:
dmi.product.family: 103C_5336AN HP EliteBook
dmi.product.name: HP EliteBook X G2a 14 inch Notebook Next Gen AI PC
dmi.product.sku: D72PQUT#ABA
dmi.product.version: SBKPFV3
dmi.sys.vendor: HP
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2163001
Title:
HP EliteBook X G2a (board 8EF5) — No internal audio, ACP70: BIOS sets
acp-audio-config-flag=0x10
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