Support for NUX MG-300 USB interface

[Mike Oliphant]

After some more testing, it seems to be working inconsistently on my
Raspberry Pi. Sometimes it works perfectly, sometimes only capture works,
and sometimes only playback works.

The behavior seems reminiscent of some of the problems with implicit
feedback devices which have now been fixed.

Mike

On Thu, Jan 21, 2021 at 11:04 AM Mike Oliphant <oliphant at nostatic.org>
wrote:

> As a last ditch effort before returning the device, I tried the clock
> patch on a Raspberry Pi 4 running an older kernel, and... it works.
>
> The kernel version is "Linux raspberrypi 4.19.89-v7l+" and is from late
> February 2020.
>
> Maybe a change between then and now broke something? I know there have
> been a *lot* of changes since then, though...
>
> Mike
>
> On Wed, Jan 20, 2021 at 1:47 PM Mike Oliphant <oliphant at nostatic.org>
> wrote:
>
>> Yeah, I tried every possible permutation of mute/volumes on the mixer
>> controls.
>>
>> Thanks for submitting the patches. Maybe someone else will have better
>> luck down the road.
>>
>> Mike
>>
>> On Wed, Jan 20, 2021 at 1:38 PM Takashi Iwai <tiwai at suse.de> wrote:
>>
>>> On Wed, 20 Jan 2021 22:17:35 +0100,
>>> Mike Oliphant wrote:
>>> >
>>> > 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.
>>>
>>> So, even if you unmute and raise both mixers, it didn't help, right?
>>> I took a look at the lsusb output, but I couldn't find anything else
>>> suspicious.
>>>
>>> > 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.
>>>
>>> OK, I'll submit two fix patches.
>>>
>>>
>>> thanks,
>>>
>>> Takashi
>>>
>>