Support for NUX MG-300 USB interface

[Mike Oliphant]

I spent a fair bit of time debugging the code setting/getting mixer control
values, and I can't see anything that seems to be operating incorrectly.

Unless you have any other suggestions, I'm going to admit defeat and return
the audio interface.

It is probably worth committing the clock selector patch - it at least made
capture work, and it may help with other audio interfaces.

Thanks for your help,

Mike



On Wed, Jan 20, 2021 at 6:33 AM Takashi Iwai <tiwai at suse.de> wrote:

> On Tue, 19 Jan 2021 18:40:04 +0100,
> Mike Oliphant wrote:
> >
> > Your mixer.c patch does get rid of the RANGE errors. No change to
> behavior,
> > though.
> >
> > I'd already tried setting "implicit_fb=1" even though I didn't expect it
> to
> > work, since there is a separate feedback endpoint. I just tried it again
> - it
> > doesn't seem to hurt anything, but it doesn't help either.
> >
> > Capture seems to be working perfectly with the clock patch - I'm not
> sure why
> > I was initially getting noisy input.
> >
> > I checked "/proc/asound/card*/pcm*/sub*/status" during playback, and the
> > pointer seems to be moving forward as it should. All indications are
> that the
> > system thinks playback is working fine.
> >
> > One interesting piece of information - alsamixer shows two stereo outputs
> > ("pcm" and "pcm1"). Not sure why there are two - maybe output is going
> to the
> > wrong one?
>
> You might need to unmute and increase both.  The first one should be a
> master volume/switch while the second one is for the stereo channels.
>
> Naming the mixer elements properly for USB-audio is a really tough
> task.  Many firmware don't set the right strings and a guess work
> doesn't fit to all.  But certainly there are some rooms for
> improvements there.
>
>
> Takashi
>