# Kernel 7 Audio Troubleshooting for Dell XPS 17 9700

## Symptom
On the Niri live ISO booting kernel 7, audio shows only HDMI devices and "Dummy Output" in `wpctl status`. Internal speakers and headphone jack do not appear.

## Root Cause
The XPS 17 9700 is a Dell SoundWire platform requiring **SOF + SoundWire** for internal audio on modern Linux kernels. The issue is **not** PipeWire misconfiguration. Common causes are:

1. Kernel driver stack selection issue (wrong path selected at boot)
2. Missing or mismatched SOF firmware/topology
3. Missing or mismatched `sof-soundwire` UCM profiles
4. A kernel SoundWire regression

## Diagnostic Steps

### 1. Verify the driver stack is loading
Boot into the live ISO and check which driver is active:

```bash
# Should show SOF driver for internal audio
lsmod | grep -E '^sof|^snd_sof'

# Should show the SoundWire machine driver
lsmod | grep -E 'sof_sdw|sof.*mach'

# Check kernel logs for SoundWire errors
sudo dmesg | grep -Ei 'soundwire|sdw|sof.*error|topology.*-22'
```

### 2. Test explicit SOF driver selection
If internal audio is missing, the kernel's auto-detection may have selected the wrong path. At the GRUB/boot menu, edit the kernel command line and add:

```
snd-intel-dspcfg.dsp_driver=3
```

This explicitly forces SOF (value `3`) for the audio stack. Options are:
- `0`: auto (kernel's default)
- `1`: legacy HDA
- `3`: SOF (correct for this laptop)
- `4`: AVS

Then boot and re-check:
```bash
wpctl status
```

### 3. Verify package completeness
Ensure the live image has the required audio support packages:

```bash
xbps-query -l | grep -E '^ii.*sof-firmware|alsa-ucm-conf|alsa-utils'
```

Expected output should include:
- `sof-firmware` (Sound Open Firmware binaries and topology)
- `alsa-ucm-conf` (Use Case Manager profiles for `sof-soundwire`)
- `alsa-utils` (ALSA utilities and initial mixer state)

### 4. Check PipeWire/WirePlumber state
Once the kernel exposes the internal audio devices (they should appear in `wpctl status`), verify PipeWire is reading them correctly:

```bash
# List all devices seen by PipeWire
pw-cli ls Device

# Check WirePlumber's ALSA monitor for errors
journalctl -u wireplumber.service -n 50

# Manually re-scan if needed
pw-cli list-objects Module | grep monitor
```

## If It Still Fails

### Check for a kernel regression
Recent kernel versions 6.9 and 6.10 had SoundWire regressions affecting XPS-series Dell laptops. These were fixed in:
- 6.9.x (fixed in 6.9 stable releases)
- 6.10.11+

If kernel 7.x shows the same symptoms, check the [SOF upstream issues](https://github.com/thesofproject/linux/issues) for similar reports.

### Compare against a known-good kernel
If kernel 7 still fails with `dsp_driver=3`:
1. Boot with the fallback kernel 6 (available in the Niri live ISO GRUB menu)
2. Test audio on kernel 6
3. If audio works on kernel 6 but not kernel 7, there is likely a kernel-7-specific regression

Report findings to:
- [SOF upstream](https://github.com/thesofproject/linux/issues)
- [Void Linux](https://github.com/void-linux/void-packages)

### Manual ALSA routing (for microphone issues)
If speakers work but the internal microphone does not, manually set the mic input mux:

```bash
amixer --card 1 set 'rt715 ADC 24 Mux' 'DMIC3'
```

Then persist the state:
```bash
sudo alsactl store
```

## References

- [ArchWiki: Dell XPS 17 (9700)](https://wiki.archlinux.org/title/Dell_XPS_17_(9700))
- [ArchWiki: Sound Open Firmware](https://wiki.archlinux.org/title/Sound_Open_Firmware)
- [SOF upstream issue 4999: 6.8.9→6.9.0 regression](https://github.com/thesofproject/linux/issues/4999)
- [Kernel docs: intel-dsp-config](https://github.com/torvalds/linux/blob/master/sound/hda/core/intel-dsp-config.c)
- [XPS 9700 Ubuntu fix guide](https://askubuntu.com/questions/1270442/no-sound-on-xps-17-9700)

## Live ISO Packages

The mainline-niri Niri live ISO includes:
- `sof-firmware`: Intel SOF binary and topology files
- `alsa-ucm-conf`: ALSA Use Case Manager profiles, including `sof-soundwire`
- `pipewire` and `wireplumber`: Session and policy management
- `linux-mainline`: Kernel 7.x with SOF support
- `linux`: Kernel 6.x fallback entry in GRUB

The build ensures both kernels are available to test audio driver behavior across kernel versions.