[LAU] manual ALSA device rescan

[Brent Busby]

This problem is trivial, but maybe there's a trivial solution...

I have an Edirol UM-3EX USB MIDI interface that I sometimes pass through
to guest OS's in QEMU, which works surprisingly well at letting the
guest use the real world MIDI hardware.

However, QEMU does a reset on the device, which seems to cause it to get
a new USB device number and disappear from ALSA's view.  If I physically
unplug and replug it, ALSA picks it up again and everything is fine, and
I don't even need to reboot.

It bugs me that I even need to do that.  (I told you it was trivial.)
Is there a way to make ALSA scan for new devices manually?  I'm on
Gentoo for what it's worth, but that may not matter.  Obviously, ALSA
has some way of picking new devices up or else replugging wouldn't
work.  I'm just thinking I should be able to trigger that myself, and
also it may be educational for me to learn how ALSA does this.

-- 
- Brent Busby	+ ===============================================
		+ "The introduction of a new kind of music must
-- Studio    --	+  be shunned as imperiling the whole state, for
-- Amadeus/  --	+  styles of music are never disturbed without
-- Keycorner --	+  without affecting the most important political
-- Recording --	+  institutions."    --Plato, "Republic"
----------------+ ===============================================
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 658 bytes
Desc: not available
URL: <https://lists.linuxaudio.org/archives/linux-audio-user/attachments/20190729/bd8d7f3b/attachment.sig>