PreSonus Quantum 2626 Linux driver

Experimental out-of-tree ALSA PCI driver for the PreSonus Quantum 2626 Thunderbolt interface (1c67:0104). The project is based on static protocol recovery from the macOS DriverKit extension and bounded tests on owned hardware.

Linux audio works

Important

The Quantum 2626 is producing real audio on Linux. The current driver initializes the interface to its solid-blue ready state, plays ordinary desktop audio through PipeWire, captures real input data, and runs playback and capture concurrently on physical Quantum 2626 hardware.

This is no longer a fake-pointer or register-probing proof of concept. The driver uses the recovered TCI mailbox, hardware DMA page tables, real audio interrupts, and the hardware position counter. The result has been heard through the interface's headphone output and exercised through both direct ALSA and normal desktop applications.

What works today

• The recovered TCI mailbox reaches the device-ready state; the interface's indicator is solid blue after the Linux handshake.
• Direct ALSA playback is stable in the proven 48 kHz, 26-channel, S32_LE, 128-frame-period configuration.
• Playback channels 1 and 2 are physically confirmed through the left and right headphone outputs.
• Ordinary YouTube audio plays through the Quantum PipeWire sink and is physically audible through the connected headphones.
• The bundled ALSA UCM profile exposes Main plus every 48 kHz output pair over a shared multichannel stream. WirePlumber publishes all 13 named playback sinks.
• A 26-channel capture PCM is live-proven through direct ALSA and concurrent PipeWire playback/capture. UCM publishes all 26 Mic/Line/S/PDIF/ADAT inputs as independent mono sources—including a standalone, live-tested Line Input 5 instead of a forced 5/6 stereo pair.
• Playback and capture run concurrently through the shared hardware engine; bounded duplex tests completed without an xrun, DMA timeout, or stop failure.

The current live-proven contract remains fixed at 48 kHz. The repository source now implements native 44.1, 48, 88.2, 96, 176.4, and 192 kHz selection with the recovered 26/18/8-channel profiles, but that new clock-changing path has passed only offline build and static checks. Other analog outputs, physical S/PDIF/ADAT paths, and every non-48 kHz profile still need bounded hardware validation.

The canonical evidence and current limitations are in notes/CURRENT_STATUS.md. The exact channel layout is in notes/CHANNEL_ROUTING.md.

Build

make -C driver

The build requires headers for the running kernel. Compilation proves source compatibility only; it does not prove a hardware path safe.

Install

From driver/, the install target places both the kernel module and the ALSA UCM desktop profile:

cd driver
sudo make install
sudo modprobe snd-quantum2626

Module load/unload, audio-service changes, playback, capture, and hardware probing are live tests. Follow docs/agents/hardware-testing.md and establish a fresh test boundary before running them.

Repository map

Path	Purpose
driver/	Kernel module and build/install targets.
alsa/	UCM desktop routing for the proven 48 kHz duplex layout.
notes/CURRENT_STATUS.md	Canonical consolidated hardware and implementation status.
notes/CHANNEL_ROUTING.md	Vendor channel order plus Linux playback-pair and mono-input bindings.
notes/TCI_PROTOCOL.md	Recovered mailbox registers and command framing.
scripts/ghidra/	Reproducible analysis helpers; proprietary inputs stay outside the repo.
docs/agents/	Agent guidance and durable task routing.

Known limits

• Only the Quantum 2626 PCI ID is enabled; related Quantum models are not claimed or probed by this driver.
• The tracked UCM desktop profile remains fixed to the live-proven 48 kHz, 26-channel layout. Direct ALSA/DAW use of the new native-rate source requires the matching full raw frame: 26 channels at 44.1/48, 18 at 88.2/96, and 8 at 176.4/192 kHz.
• No mixer controls, MIDI, live-proven high-rate profile, or hot-removal proof exists yet.
• End-to-end latency and release-performance tuning are not complete; no sub-millisecond or professional real-time performance claim is made yet.
• Capture is live-proven at 48 kHz through direct ALSA and PipeWire duplex tests.
• ADAT routing is statically identified, not physically confirmed on Linux.

This repository contains no proprietary driver binary or bulk decompiler output. Local reverse-engineering artifacts are intentionally ignored.