[alsa-devel] UCM representation questions

Mark Brown broonie at opensource.wolfsonmicro.com
Fri May 27 03:31:59 CEST 2011

On Thu, May 26, 2011 at 10:13:21AM -0700, Stephen Warren wrote:

> My thought process here was that conflicting devices are probably less
> common than non-conflicting devices. At least, it seems like that'd be
> the default assumption of someone writing a UCM file. So, if we list
> ConflictingDevice(s), then that would often map to an empty list, and
> you could eliminate the section. If we had to list all compatible
> devices, by default you'd have to list every device in the UCM verb in
> almost all cases. That seems like more work.

> Plus, adding an optional ConflictingDevice list maintains backwards
> Compatibility with any existing UCM files, whereas adding a mandatory
> SupportedDevice list doesn't.

I tend to agree with this - the usual case is that you can have as many
devices as you like running, the reason for restricting things is more
normally usefulness rather than physical possibility.

> I wonder if allowing all lists of devices to be either inclusive
> SupportedDevice or exclusive ConflictingDevice makes sense, with the
> default being ConflictingDevice being empty, and SupportedDevice being
> the entire set of devices? Seems more complex, but probably still
> workable.

That makes sense too - if either directive is used we require an
explicit list, otherwise we assume everything is compatible.

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