[alsa-devel] Regression in Traktor Audio10 driver (snd-usb-audio) mixer flags

[Owen Williams]

Sorry to bump my own thread, but I don't know how else to report bugs to
ALSA (I think the bug tracker was abandoned a while back?).  I'm willing
to do work to diagnose and fix this problem (I'm comfortable building
kernels, doing git bisect, using gdb, etc) but I need some guidance
about how to start.

On Thu, 2015-12-31 at 13:26 -0500, Owen Williams wrote:
> Sometime between kernels 3.13 (ubuntu 14.04) and 3.19 (15.04) there was
> a regression that caused the mixer elements of the Traktor Audio10
> driver to stop responding to changes to True.  I have an older machine
> still running 14.04, and if I open alsamixer I can see and interact
> with the 8 basic boolean switches:
> 
> numid=3,iface=MIXER,name='Direct Thru Channel A'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=4,iface=MIXER,name='Direct Thru Channel B'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=5,iface=MIXER,name='Direct Thru Channel C'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=6,iface=MIXER,name='Direct Thru Channel D'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=7,iface=MIXER,name='Phono Input Channel A'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=8,iface=MIXER,name='Phono Input Channel B'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=9,iface=MIXER,name='Phono Input Channel C'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> numid=10,iface=MIXER,name='Phono Input Channel D'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> 
> 
> or I can use amixer:
> amixer -c T10 cset numid=8 on
> 
> 
> however on my newer machine, with ubuntu 15.04 and 15.10, I am unable
> to change the values to true.  I am a member of the audio group and I
> have also tried with sudo, but when I try to set the value on nothing
> happens:
> 
> $ amixer -c T10 cset numid=8 on
> numid=8,iface=MIXER,name='Phono Input Channel B'
>   ; type=BOOLEAN,access=rw------,values=1
>   : values=off
> 
> The fun part is, if I connect the card to my mac I can set startup
> conditions for these flags.  I can set them to true, and when I connect
> to my linux machines the flags start up as true.  And then, even on the
> newer kernel, I can turn them off!  But I can't turn them back on
> again.
> 
> This sound card is the one I'd like to recommend officially for the
> Mixxx DJ project so I'd really like to get to the bottom of this issue.
> 
> 
> thanks,
> Owen Williams
> 
> A Lead Developer, Mixxx.org