Detailed Root Cause Analysis

Modern high-end laptops no longer use traditional Intel HDA (High Definition Audio) buses for internal speakers. They route audio over Intel SoundWire (SDW), a complex multi-link serial bus that requires the operating system kernel to know exactly which chip is wired to which physical link on the motherboard before it can load the DSP configuration.

• Component: Linux Kernel ASoC Subsystem / Intel SoundWire Machine Driver Match Matrix
• Platform: Intel Arrow Lake-S (ARL-S) Audio Control Unit (8086:7f50 via sof-audio-pci-intel-mtl)
• Hardware Configuration: Realtek RT713 Codec (Link 0) + Dual Realtek RT1320 Amplifiers (Link 2)
• Symptom: Analog audio endpoints fail to map, resulting in a systemic user-space "Dummy Output" fallback.
• Root Cause: The hardcoded kernel match table macro snd_soc_acpi_intel_arl_machines[] inside sound/soc/intel/common/soc-acpi-intel-arl-match.c lacks an entry mapping a part_id 0x0713 on Link 0 aggregated with part_id 0x1320 on Link 2 for the Arrow Lake architecture.

[Motherboard ACPI/DSDT] 
       │
       ▼ Reports valid hardware on SoundWire Bus:
       │  • Link 0: Realtek RT713 (0x0713)
       │  • Link 2: Dual RT1320 Amps (0x1320)
       │
[Kernel: snd-soc-acpi-intel-match.ko] 
       │
       ▼ Scans 'soc-acpi-intel-arl-match.c' Table
       │  ❌ FAIL: No entry matches 0x0713 (L0) + 0x1320 (L2) 
       │  (Only 0x0722 + 0x1320 entries exist upstream)
       │
[Kernel: sof-audio-pci-intel-mtl] 
       │
       ▼ Drops SoundWire initialization entirely
       │  Logs: "No SoundWire machine driver found... using HDA machine driver"
       │
[ALSA / PipeWire Server]
       │
       ▼ Core fallback loops map HDMI digital ports only
          ❌ Result: Zero analog audio/mic endpoints = "Dummy Output"

The Specific Code Fix Required

To resolve this, sound/soc/intel/common/soc-acpi-intel-arl-match.c needs to be modified to append a new descriptor block to the snd_soc_acpi_intel_arl_machines array.

It needs to explicitly define a new link configuration struct where:

link_mask targets Link 0 and Link 2.

request_codec_id searches for the string matching 025d0713 (Realtek RT713).

The aggregated endpoints attach the 025d1320 (RT1320) amplifiers.

The drv_name is bound to the standard Intel SOF SoundWire aggregation machine driver (sof_sdw).

Without this specific patch landing in a stable Canonical kernel build, the motherboard's internal audio engines will remain completely paralyzed to the Linux OS.