tree 2c26fc2be5cdaff4aee3faf7b3f0565c1298acff
parent 5a222e8494524d04cc8de63726644759e5b132f7
author Andrew Chant <achant@google.com> 1521858324 -0700
committer Takashi Iwai <tiwai@suse.de> 1521881434 +0100

ALSA: usb-audio: update clock valid control

Make the "clock valid" control a global control instead of a mixer
so that it doesn't appear in mixer applications.

Additionally, remove the check for writeability prohibited by spec, and
Use common code to read the control value.

Tested with a UAC2 Audio device that presents a clock validity
control.  The control still shows up in /proc usbmixer but not
in alsamixer.

Signed-off-by: Andrew Chant <achant@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>