[alsa-devel] UCM {Supported,Conflicting}Device confusion

Juho Hämäläinen juho.hamalainen at tieto.com
Wed May 29 12:55:38 CEST 2013


Firstly as a sidenote, Supported/Conflicting is checked only one-way, if 
say devices A and B are enabled and say B has ConflictingDevice "C", and 
device C doesn't list anything, enabling of C is possible (and after 
that disabling C is not possible before B is disabled first).

Now, looking at the way SupportedDevice and ConflictingDevice are 
implemented in ucm and I came to following conclusion:

If no SupportedDevice or ConflictingDevice: All devices and combinations 
are compatible, so implicit "SupportedDevice ALL".

If SupportedDevice is listed: Device can be enabled as long as at least 
one enabled device is in SupportedDevice list.

If ConflictingDevice is listed: Device can be enabled if none of active 
devices are in ConflictingDevice list (noting aforementioned limit in 
checking this)

This is at least how I figured all combinations of multiple devices can 
be defined with only zero or one either SupportedDevice or 
ConflictingDevice entry per device.

Did I understand this right?


More information about the Alsa-devel mailing list