Re: USB Audio: AlphaTheta / Pioneer DJM-S11 (2b73:0037) fails UAC2 clock enumeration

[Geraldo Nascimento <geraldogabriel@gmail.com>]

On Tue, Dec 23, 2025 at 08:48:49PM +0100, Federico Beffa wrote:
> Hello ALSA developers,

Hi Federico!

> 
> I am investigating Linux support for the AlphaTheta / Pioneer DJM-S11 
> mixer and would like to report the current behavior and ask for guidance 
> on possible driver or quirk development.
> 
> Device:
> Vendor ID: 2b73 (AlphaTheta Corporation)
> Product ID: 0037 (DJM-S11)
> Firmware: bcdDevice 1.05
> USB speed: High Speed (480 Mbps)
> 
> Environment:
> NixOS 25.11
> Kernel: Linux 6.12.62
> Driver: snd-usb-audio
> 
> Summary of the issue:
> The DJM-S11 enumerates correctly on USB and exposes AudioControl, 
> AudioStreaming, MIDI, and HID interfaces. However, ALSA fails to create 
> any PCM devices, and the mixer does not appear in aplay -l.
> 
> Kernel log shows the following errors during enumeration:
> 
> parse_audio_format_rates_v2v3(): unable to retrieve number of sample 
> rates (clock 1)
> Quirk or no altset; falling back to MIDI 1.0
> 
> As a result, only MIDI and HID interfaces are exposed; audio streaming 
> is disabled.
> 
> Descriptor observations:
> 
> - The device advertises itself as USB Audio Class 2.0 (bcdADC 2.00, 
> InterfaceProtocol 32).
> - A CLOCK_SOURCE descriptor is present (ClockID 1) with Clock Frequency 
> Control marked as read/write.
> - No valid clock rate list can be retrieved by the driver (GET_RANGE 
> appears to fail).
> - Audio streaming endpoints do exist:
> - Playback: 14 channels, 24-bit PCM, isochronous async OUT
> - Capture: 10 channels, 24-bit PCM, isochronous async IN (implicit feedback)
> 
>  From inspection of lsusb -vv, this appears to be a case where the 
> device advertises UAC2 but requires vendor-specific clock initialization 
> before audio streaming becomes usable. Without that, snd-usb-audio 
> correctly refuses to expose PCM devices.
> 
> I can provide the full lsusb -vv output and additional logs if helpful.
> 
> Questions:
> 
> 1. Is this a known pattern for newer Pioneer/AlphaTheta mixers, and has 
> similar hardware been handled via ALSA quirks in the past?

see sound/usb/quirks-table.h

> 2. Would it be acceptable to experiment with a quirk that forces a fixed 
> sample rate (e.g. 48 kHz) and bypasses clock queries, for 
> development/testing purposes?

Actually, for production.

It shouldn't be too hard to produce a quirk from the datasheet of the
Pioneer DJM-S11, and even if you're unlucky to be missing a few details,
trial and error will be your best friend.

Thanks,
Geraldo Nascimento

> 3. Or does this class of device realistically require vendor-specific 
> control handling beyond what snd-usb-audio quirks can support?
> 
> I am interested in starting development work on this (initially 
> out-of-tree) and would appreciate any guidance on the most appropriate 
> direction.
> 
> Thank you for your time and for ALSA’s continued work.
> 
> Best regards,
> Federico