tree 666892dd62a26bf38733d79386b5c5909c896b93
parent 5bef44f9b4849d1c3af4ed2ea93061ff56e68cd7
author Mark Brown <broonie@opensource.wolfsonmicro.com> 1307979749 +0100
committer Mark Brown <broonie@opensource.wolfsonmicro.com> 1307987973 +0100

ASoC: Add weak routes for sidetone style paths

Normally DAPM will power up any connected audio path. This is not ideal
for sidetone paths as with sidetone paths the audio path is not wanted in
itself, it is only desired if the two paths it provides a sidetone between
are both active. If the sidetone path causes a power up then it can be
hard to minimise pops as we first power up either the sidetone or the main
output path and then power the other, with the second power up potentially
introducing a DC offset.

Address this by introducing the concept of a weak path. If a path is marked
as weak then DAPM will ignore that path when walking the graph, though all
the relevant controls are still available to the application layer to allow
these paths to be configured.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>