UCM HiFi profile fails on hardware with Master volume instead of Headphone volume controls (ASUS ZenBook UX425EA)

[GitHub issues - opened <github@alsa-project.org>]

alsa-project/alsa-ucm-conf issue #687 was opened from akincano:

### Hardware Information
- Laptop: ASUS ZenBook UX425EA_UX425EA
- Audio Controller: Intel Tiger Lake-LP Smart Sound Technology
- Audio Controller (PCI ID: 0x8086:0xa0c8)
- Codec: Realtek ALC294 (Vendor ID: 0x10ec0294, Subsystem ID: 0x10431cee)
- Kernel: 6.18.5.arch1-1
- Distribution: Arch Linux

### Software Versions
```bash
alsa-ucm-conf 1.2.15.2-1
sof-firmware 2025.12-1
linux 6.18.5.arch1-1
```

### Problem Description
The SOF HiFi profile fails to create speaker/headphone audio devices on this hardware. WirePlumber reports:
```bash
spa.alsa: No sink and source at HiFi: Headphones
```
The HiFi profile shows as available: no and only HDMI outputs are exposed, with no analog audio devices.

### Root Cause
**This is a UCM configuration issue**, not a kernel driver issue. The problem is that /usr/share/alsa/ucm2/HDA/HiFi-analog.conf checks for ALSA controls that don't exist on this hardware.

**ALSA controls exposed by this hardware (identical for both SOF and HDA):**
```bash
numid=3,iface=CARD,name='Speaker Phantom Jack'
numid=2,iface=MIXER,name='Master Playback Switch'
numid=1,iface=MIXER,name='Master Playback Volume'
[HDMI/IEC958 controls omitted for brevity]
```

**Controls the UCM config expects but don't exist:**
- Headphone Playback Volume ❌ (only Master Playback Volume exists)
- Headphone Playback Switch ❌ (only Master Playback Switch exists)
- Headphone Jack ❌ (only Speaker Phantom Jack exists)

**UCM config logic that fails:**
In /usr/share/alsa/ucm2/HDA/HiFi-analog.conf:
```bash
If.hpvol {
    Condition {
        Type ControlExists
        Control "name='Headphone Playback Volume'"
    }
    False.Define.hpvol ""
}

If.hp {
    Condition {
        Type String
        Empty "${var:hpvol}"
    }
    False.SectionDevice."Headphones" {
        # ... creates headphone device
    }
}
```
Because Headphone Playback Volume doesn't exist, hpvol is set to empty string, and the If.hp condition prevents the headphone device from being created.

Similarly, the jack detection logic checks for:
```bash
Define.hpjack "Headphone Jack"
If.hpjack {
    Condition {
        Type ControlExists
        Control "iface=CARD,name='Headphone Mic Jack'"
    }
    # ... falls back to checking 'Front Headphone Jack'
}
```
But never checks for Speaker Phantom Jack, which is what this hardware exposes.

### Working Configuration (Legacy HDA Driver)
With the legacy snd_hda_intel driver (forced via blacklisting SOF), PulseAudio's built-in profile logic correctly handles this hardware:

**Working profile:** output:analog-stereo+input:analog-stereo

**Exposed ports:**
- analog-output-speaker: Speakers (uses Master Playback Volume/Switch)
- analog-output-headphones: Headphones (uses Master Playback Volume/Switch)
- Automatic jack detection via Speaker Phantom Jack

The legacy HDA driver works because PulseAudio has fallback logic that handles hardware with only Master volume controls, but SOF's UCM-based configuration doesn't have this fallback.

### Proposed Solution
The UCM configuration needs to be updated to handle hardware that only exposes Master Playback Volume/Switch instead of dedicated Headphone controls.

**Option 1: Add fallback logic to HiFi-analog.conf**

Check for Master Playback Volume when Headphone Playback Volume doesn't exist:
```bash
If.hpvol {
    Condition {
        Type ControlExists
        Control "name='Headphone Playback Volume'"
    }
    False.If.master {
        Condition {
            Type ControlExists
            Control "name='Master Playback Volume'"
        }
        True.Define.hpvol "Master"
    }
}
```

Similarly for jack detection, check Speaker Phantom Jack:
```bash
If.hpjack {
    Condition {
        Type ControlExists
        Control "iface=CARD,name='Headphone Mic Jack'"
    }
    True.Define.hpjack "Headphone Mic Jack"
    False.If.front {
        Condition {
            Type ControlExists
            Control "iface=CARD,name='Front Headphone Jack'"
        }
        True.Define.hpjack "Front Headphone Jack"
        False.If.speaker {
            Condition {
                Type ControlExists
                Control "iface=CARD,name='Speaker Phantom Jack'"
            }
            True.Define.hpjack "Speaker Phantom Jack"
        }
    }
}
```

**Option 2: Create a specific profile for this hardware**

Create a UCM profile specifically for Tiger Lake systems with Realtek ALC294 that only expose Master controls.

**Option 3: Update SOF topology**
If this is a SOF topology issue, update the topology to expose proper Headphone controls instead of just Master.

### Additional Debug Information
**Pin 0x21 configuration (headphone jack):**
```bash
Node 0x21 [Pin Complex] wcaps 0x40058d: Stereo Amp-Out
  Pincap 0x0001001c: OUT HP EAPD Detect
  Pin Default 0x411111f0: [N/A] Speaker at Ext Rear
    Misc = NO_PRESENCE
  Pin-ctls: 0x00:
  Unsolicited: tag=00, enabled=0
```
The pin is capable of jack detection (EAPD Detect in capabilities) but is misconfigured as "N/A" with "NO_PRESENCE". However, the jack detection still works via the Speaker Phantom Jack ALSA control.

**Full codec information:** Available upon request

**Full WirePlumber logs:** Available upon request

### Impact
This affects all ASUS ZenBook UX425EA users (and potentially other laptops with similar hardware configurations) running SOF. Users must either:

1. Use pro-audio profile (no automatic headphone/speaker switching)
2. Blacklist SOF and force legacy HDA driver (not a long-term solution)

### Related Issues
This was initially reported in #686 which was closed as a kernel issue, but further investigation revealed it's actually a UCM configuration problem. The kernel driver is exposing the ALSA controls correctly; the UCM config just doesn't know how to handle this hardware configuration.

Issue URL     : https://github.com/alsa-project/alsa-ucm-conf/issues/687
Repository URL: https://github.com/alsa-project/alsa-ucm-conf