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Groups > linux.debian.kernel > #94761

Bug#1152888: MOTU M2 also affected by 6.12.115 USB audio regression

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Dear Maintainer,

I can independently confirm this regression on Debian 13 (Trixie) using a MOTU M2 audio interface.

Hardware:

Motherboard: MSI MAG B660 Tomahawk WiFi DDR4
CPU: Intel Core i7-12700
USB controller: Intel xHCI
Audio interface: MOTU M2 [07fd:000b]
USB audio driver: snd_usb_audio

Kernel comparison:

6.12.113+deb13-amd64: WORKING
6.12.115+deb13.1-amd64: BROKEN

The failure initially appeared following an upgrade from Debian 12 Bookworm, kernel version 6.1.54 to Debian 13 Trixie.
After extensive troubleshooting, I tried installing and booting Linux 6.12.113. Audio playback through the MOTU M2 was restored, without changing the Debian 13 userspace or audio configuration.

Symptoms under 6.12.115:

-ALSA successfully recognizes the MOTU M2, and PipeWire exposes the playback device.
-When the MOTU is selected as the default audio output, there is no sound from the monitor headphones or speakers.
-When selected as the default audio output, attempting to play videos in Firefox such as YouTube results in playback stalling indefinitely.
-Selecting my Bluetooth headphones or HDMI audio outputs restored normal YouTube playback.
-Switching the MOTU to PipeWire's Pro Audio profile allowed YouTube playback to proceed, but no audio is produced.
-Direct ALSA playback remains silent even after stopping PipeWire and WirePlumber.

Direct ALSA reproduction:

After stopping WirePlumber and PipeWire:

speaker-test -D plughw:3,0 -c 2 -r 48000 -t sine -f 440

The playback stream reports RUNNING, but the ALSA hardware pointer never advances.

Output of /proc/asound/card3/pcm0p/sub0/status:

state: RUNNING
delay: 48000
avail: 0
avail_max: 0
hw_ptr: 0
appl_ptr: 48000
The same values were observed after waiting several seconds.

Additional troubleshooting notes:

-Reloading snd_usb_audio with lowlatency=0 did not resolve the problem.
-Running ALSA capture simultaneously with playback using arecord and speaker-test did not cause hw_ptr to advance
-The MOTU's USB audio playback endpoint uses asynchronous transfers and implicit feedback.
-ALSA arecord recordings produce nonzero audio samples. A controlled input test showed an approximately 15.2 dB RMS increase on channel 2 (mic channel) when producing an input signal. Although playing the .wav file back through my headphones it sounded silent.
-The input meters on the MOTU M2 audio interface itself respond normally.
-No obvious USB audio errors were observed in the kernel logs during the playback failure.
-The M2 and M4 share USB vendor/product ID 07fd:000b, and this appears to be the same regression described in this report.

Thank you.
-Christopher Ludwin

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Thread

Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Benjamin Scherrer <benjamin@wagnerbrutal.de> - 2026-11-02 22:20 +0100
  Processed: Re: Bug#1152888: Regression: MOTU M4 USB audio  playback fails with EIO on Linux 6.12.115 (works on 6.12.113) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-11-03 17:20 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Salvatore Bonaccorso <carnil@debian.org> - 2026-11-03 17:20 +0100
    Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Benjamin Scherrer <benjamin@wagnerbrutal.de> - 2026-11-03 23:50 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Sebastian Kiesel <sebastian-debian-reportbug@skiesel.de> - 2026-11-03 17:40 +0100
  Bug#1152888:  Michele Zelioli <michele.zelioli@ik.me> - 2026-11-03 21:50 +0100
  Bug#1152888: MOTU M2 also affected by 6.12.115 USB audio regression Christopher Ludwin <cjludwin@pm.me> - 2026-11-03 23:10 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with  EIO on Linux 6.12.115 (works on 6.12.113) "smg" <smgdream@foxmail.com> - 2026-11-04 04:20 +0100
  Processed: Re: Bug#1152888: Regression: MOTU M4 USB audio  playback fails with EIO on Linux 6.12.115 (works on 6.12.113) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-11-04 06:00 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with  EIO on Linux 6.12.115 (works on 6.12.113) "smg" <smgdream@foxmail.com> - 2026-11-04 16:20 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Benjamin Scherrer <benjamin@wagnerbrutal.de> - 2026-11-04 17:30 +0100
  Bug#1152888: Regression: MOTU M4 USB audio playback fails with EIO on Linux 6.12.115 (works on 6.12.113) Sebastian Kiesel <sebastian-debian-reportbug@skiesel.de> - 2026-11-04 18:50 +0100
  Processed: Re: Bug#1152888: Regression: MOTU M4 USB audio  playback fails with EIO on Linux 6.12.115 (works on 6.12.113) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-11-05 07:50 +0100

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