Re: [PATCH] ALSA: usb-audio: Add quirk for Yamaha ZG02

[Takashi Iwai <tiwai@suse.de>]

On Wed, 04 Nov 2026 01:39:38 +0100,
Riley via B4 Relay wrote:
> 
> From: Riley <riley.redeker@gmail.com>
> 
> The Yamaha ZG02 game streaming mixer (0499:1516) exposes UAC2 audio
> streaming interfaces with a vendor-specific interface class. Only its
> MIDI interfaces get bound today: the Yamaha catch-all QUIRK_AUTODETECT
> entry rejects the PCM interfaces because create_auto_pcm_quirk()
> expects a UAC1-sized FORMAT_TYPE descriptor (bLength >= 8), while the
> ZG02 has the 6-byte UAC2 one. As a result no PCM device is created.
> 
> The interface layout matches the Steinberg UR22 (0499:1509):
> 
>   0: UAC2 AudioControl (vendor class), clock source ID 1
>   1: playback, 10ch S32_LE 48kHz, async isochronous OUT
>   2: capture, 4ch, isochronous IN used as implicit feedback
>   3: Yamaha MIDI
>   4: vendor bulk interface
> 
> Add the same composite quirk and QUIRK_FLAG_GENERIC_IMPLICIT_FB for
> it. The generic UAC2 implicit feedback detection does not apply here
> because it requires USB_CLASS_AUDIO.
> 
> Tested on a 7.3 kernel with this patch applied (no quirk_alias): the
> card registers as USB0499:1516, implicit feedback is set up from EP
> 0x81, and playback (voice chat and game buses) and capture (microphone)
> work. The full channel mapping (playback 1-2 voice chat bus, 3-10 game
> bus; capture 1-2 streaming mix, 3-4 microphone) was verified with
> quirk_alias=04991516:04991509, which applies the same quirk and flag
> entries.
> 
> Assisted-by: Claude Opus 5.5
> Signed-off-by: Riley <riley.redeker@gmail.com>
> ---
> Hi,
> 
> The Yamaha ZG02 currently shows up with MIDI only and no PCM device, so
> it's unusable as a sound card on Linux.
> 
> I've been running the identical quirk via quirk_alias since 2026-11-03 in
> daily use (including voice chat), and tested this patch itself on the
> device: playback, capture and implicit feedback all work. Full lsusb -v
> output for the device is available if useful.
> 
> A UCM profile that splits the streams into Game / Chat / Microphone /
> Streaming Mix is going to alsa-ucm-conf separately.

Applied now.  Thanks.


Takashi