Support for NUX MG-300 USB interface

[Takashi Iwai]

On Sun, 17 Jan 2021 19:56:01 +0100,
Mike Oliphant wrote:
> 
> I recently got a NUX MG-300 USB guitar fx interface with high hopes that it
> would work in Linux. It is supposed to be class-compliant, and works in iOS
> and macOS without a driver.
> 
> Unfortunately, while it is recognized as a USB audio device by Linux, it is
> not working.
> 
> The core issue seems to be that "stream0" reports no playback rates. dmesg
> also shows errors, including "__uac_clock_find_source(): selector reported
> illegal value".
> 
> Any help identifying the issue would be much appreciated. I have some
> experience troubleshooting the USB audio kernel code and am happy to try
> doing so if I can get a nudge in the right direction.
> 
> Output from "stream0", dmesg, and lsusb follows.

Did you try the latest 5.11-rc kernel?  There have been lots of
changes in USB-audio and this might work better there.

If it still doesn't work with 5.11-rc, please try to enable the debug
option, e.g. boot with snd_usb_audio.dyndbg=+p boot option, plug the
device, and get the kernel logs (at plugging and during the audio
operations).


thanks,

Takashi