ASoC: Support leaving paths enabled over system suspend

Some devices can usefully run audio while the Linux system is suspended.
One of the most common examples is smartphone systems, which are normally
designed to allow audio to be run between the baseband and the CODEC
without passing through the CPU and so can suspend the CPU when on a
voice call for additional power savings.

Support such systems by providing an API snd_soc_dapm_ignore_suspend().
This can be used to mark DAPM endpoints as not being sensitive to
system suspend. When the system is being suspended paths between
endpoints which are marked as ignoring suspend will be kept active.
Both source and sink must be marked, and there must already be an
active path between the two endpoints prior to suspend.

When paths are active over suspend the bias management will hold the
device bias in the ON state. This is used to avoid suspending the
CODEC while it is still in use.

Tested-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/sound/soc-dapm.h b/include/sound/soc-dapm.h
index 55c6d3d1894f..66ff4c124dbd 100644
--- a/include/sound/soc-dapm.h
+++ b/include/sound/soc-dapm.h
@@ -341,6 +341,7 @@ int snd_soc_dapm_get_pin_status(struct snd_soc_codec *codec, const char *pin);
 int snd_soc_dapm_sync(struct snd_soc_codec *codec);
 int snd_soc_dapm_force_enable_pin(struct snd_soc_codec *codec,
                                   const char *pin);
+int snd_soc_dapm_ignore_suspend(struct snd_soc_codec *codec, const char *pin);
 
 /* dapm widget types */
 enum snd_soc_dapm_type {
@@ -428,6 +429,7 @@ struct snd_soc_dapm_widget {
         unsigned char new:1;                    /* cnew complete */
         unsigned char ext:1;                    /* has external widgets */
         unsigned char force:1;                  /* force state */
+        unsigned char ignore_suspend:1;         /* kept enabled over suspend */
 
         int (*power_check)(struct snd_soc_dapm_widget *w);