[alsa-devel] Control interconnection information API?

Eliot Blennerhassett linux at audioscience.com
Thu Jan 1 00:01:47 CET 2009

New Year's Greetings,

something that seems to be lacking in the ALSA API, or at least the way
of describing controls (by name only), is any concept of the
connectivity between the various controls and the codecs and output

One use for such information is to build a GUI that shows this
connectivity (instead of the current bucket'o'controls approach).

Now there are a couple of special cases:

* HDA driver exports the codec widget information via a proc file,
allowing the codecgraph tool to visualise the connections.
Widgets have numeric IDs and list the IDs of widgets that connect to
their inputs.

* ASoC DAPM (which I (not being an ASoC developer or user) have mostly
been skimming over in this list).

Reading this
3. Codec Widget Interconnections. I can see that there are lists of
connections.  I'm not sure if these are visible to userspace via any API?

Can either of these schemes be generalised to all ALSA drivers?
Is there some other way to reveal the information (Connections TLV, new
API etc?)
Does anybody else thing this is worth pursuing, or is it just me?


Eliot Blennerhassett
AudioScience Inc

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