Re: [PATCH 3/3] ALSA: usb-audio: Do not expose sticky mixers

[Michal Pecio]

On Wed, 05 Aug 2026 22:32:00 +0800, Rong Zhang wrote:
> On Tue, 2026-08-04 at 23:55 +0200, Michal Pecio wrote:
> > My $.02 - was there no way to deal with this in userspace,
> > or to make it opt-in rather than opt-out?  
> 
> While userspace can ignore hardware mixers via some configurations,
> the current opt-out model is really about:
> 
>    When we can't distinguish between both, will the extra advantages
>    of exposing a broken GET_CUR mixer outweigh the disadvantages of
>    exposing a sticky one?
> 
> My answer is no.
> 
> A sticky hardware mixer breaks volume control completely. If a user
> doesn't know how to tell the audio stack to ignore it, it will be a
> terrible out-of-box experience.

Being able to work around it by using a different mixer control doesn't
sound like "completely broken" to me. It seems the whole issue is that
some mixer controls have no effect and you believe you can detect them
by changing the control a few times and seeing if the vaule read back
from HW changes accordingly. Of course, this also falsely catches mixer
controls which are write-only.

I'm not familiar with UAC and ALSA mixer APIs so I don't know, but as
the whole issue boils down to incluencing userspace mixer selection,
is there really no way to perform the same heuristic in userspace, move
the quirk list there as well and let users override it with a click?

Regards,
Michal