Missing UCM profile for AMD ACP 7.0 (Strix Halo) — Internal DMIC not functional

Hello, 
I have an issue getting the internal microphone of my MSI Raider A18 HX A9W working on either Linux Mint or Cachy OS, I tried to debug using both Gemini and Claude, to no avail, here is a summary written by Claude which I hope may help solve the issue (I am no developper)

Thanks for looking into it !

## Missing UCM profile for AMD ACP 7.0 (Strix Halo) — Internal DMIC not functional

### Summary

The internal microphone (DMIC) of the MSI Raider A18 HX A9W laptop is non-functional under Linux. The audio controller (AMD ACP 7.0, driver `snd_pci_ps`) initializes correctly and exposes the analog jack (ALC274, card 2) via HDA, but no PCM capture device is created for the internal DMIC. Investigation confirms the root cause is the absence of any UCM profile for ACP 7.0 in both the packaged `alsa-ucm-conf` and the upstream git repository.

---

### Hardware

| Field | Value |
|---|---|
| Laptop | MSI Raider A18 HX A9W |
| CPU | AMD Ryzen AI HX 30 (Strix Halo, ACP 7.0) |
| ACPI OEM ID | MSI_NB MEGABOOK 01072009 |
| ACPI DSDT compiler | INTL 20230628 |
| Audio controller | AMD ACP 7.0 — driver `snd_pci_ps` |
| Analog codec | Realtek ALC274 (HDA, jack in/out functional) |
| Internal mic | PDM/DMIC (path unknown — SoundWire or PDM DMA) |

---

### Software

| Component | Version |
|---|---|
| OS | CachyOS (Arch-based) |
| Kernel | 6.19.11-1-cachyos |
| alsa-ucm-conf | latest packaged |
| sof-firmware | 2025.12.2-1 (Intel only — no AMD files present) |
| PipeWire | 1.6.3 |
| WirePlumber | 1.6.3 |

---

### Observed behavior

`arecord -l` exposes only one capture device:

```
**** List of CAPTURE Hardware Devices ****
card 2: Generic_1 [HD-Audio Generic], device 0: ALC274 Analog [ALC274 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
```

No DMIC or PDM capture device is created. `wpctl status` confirms PipeWire sees no microphone source beyond the ALC274 analog input.

---

### Loaded audio kernel modules

```
snd_sof_amd_acp70      16384  0
snd_pci_ps             (loaded, 2 users — handles ACP 7.0)
snd_acp6x_pdm_dma      16384  0   ← loaded but 0 users
soundwire_amd          49152  2
snd_amd_sdw_acpi       16384  2
```

Notably, `snd_acp6x_pdm_dma` is loaded but has no users, and no SoundWire devices appear under `/sys/bus/soundwire/devices/`.

---

### UCM profile investigation

The following AMD UCM profiles are present in the packaged `alsa-ucm-conf`:

```
/usr/share/alsa/ucm2/AMD/acp-da7219-rt5682-max98357
/usr/share/alsa/ucm2/AMD/acp3x-alc5682-alc1015
/usr/share/alsa/ucm2/AMD/acp3x-alc5682-max98357
/usr/share/alsa/ucm2/AMD/acp3x-es83xx
/usr/share/alsa/ucm2/AMD/acp5x
```

The upstream git repository (`alsa-project/alsa-ucm-conf`) was also checked via the GitHub API and confirms **no `acp7x` or `acp70` directory exists**.

---

### Expected behavior

A UCM profile for AMD ACP 7.0 should be created under `/usr/share/alsa/ucm2/AMD/acp7x/` (or equivalent), enabling the internal DMIC to be exposed as a PCM capture device by the `snd_pci_ps` driver.

---

### Additional ACPI context

The ACPI tables report the following relevant SSDT entries:
- `AMD Vortex` (audio topology)
- `AMD DISCUSB4`, `AMD CPMCMN`, `AMD GPP_PME_`

The ACPI OEM string `MSI_NB MEGABOOK 01072009` may be useful for matching UCM profiles to this platform.

---

### References

- Driver `snd_pci_ps` (Pink Sardine / ACP 7.0): introduced in kernel 6.x for Strix Halo platform
- Related module: `snd_acp6x_pdm_dma` — potentially the correct PDM path for this DMIC
- No open issue found on this repository for ACP 7.0 / Strix Halo at time of filing

---

### Workaround

None currently available beyond using an external USB or 3.5mm jack microphone.

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Missing UCM profile for AMD ACP 7.0 (Strix Halo) — Internal DMIC not functional #745