On Mon, Jul 25, 2022 at 6:19 PM Tim via users <users@lists.fedoraproject.org> wrote:
On Mon, 2022-07-25 at 07:55 -0700, stan via users wrote:
> I think this is a consequence of parallel boot.  The order in which
> devices are discovered is non-deterministic.

Or, at all.  Occasionally my system doesn't find any audio hardware.

Many of us are in this "which card?" boat, because of modern hardware
being quite different from ye olde.  There's the on-board sound, which
may or may not have anything plugged into it (mine doesn't).  A HDMI
video monitor which may support sound (mine does).  And we may (I do)
have some USB audio hardware plugged in.  While I could disable the on-
board sound (assuming that a UEFI option really disables it and the OS
doesn't find it again), I can't disable the HDMI audio and it is useful
to be able to manually select it, some times.

Audio devices (like disk partitions) should have UUID's so order of discovery
can be ignored.
 

Somehow it's supposed to determine which one to use.  And we'd hope
that once we've set a preference in our login account (e.g. using
whatever pulseaudio volume control app applies, in my case I'm using
"mate-volume-control") it would stick.

Ideally, these volume control apps need improving so that they clearly
identify hardware precisely (not configure things to use the first
found device method, when *we* know that's not a fixed answer), and
write the config in such a place that it's paid attention to.

I've had a look at the link in your next message:
https://alsa.opensrc.org/MultipleCards  But I may as well be reading
NASA specs on the space shuttle, there's a presumption of prior
knowledge.

It would be helpful to have a tutorial "How to manage multiple audio
devices" using slots. 

The capabilities to get around the order in which devices are discovered
is there, but the user tools need a higher-level way to present and manage
the priority and switch between devices.  I suspect a really effective solution
might require some changes at the hardware level to support UUID's that
would be the same when a (USB) device is moved to a different system.

--
George N. White III