[ALSA] hda-intel - Add POWER_SAVE option

Added CONFIG_SND_HDA_POWER_SAVE kconfig.  It's an experimental option
to achieve an aggressive power-saving.  With this option, the driver
will turn on/off the power of each codec and controller chip dynamically
on demand.
The patch introduces a new module option 'power_save'.  It specifies
the second of time-out for automatic power-down.  As default, it's
10 seconds.  Setting 0 means to suppress the power-saving feature.
The codec may have analog-input loopbacks, which are usually represented
by mixer elements such as 'Mic Playback Switch' or 'CD Playback Switch'.
When these are on, we cannot turn off the mixer and the codec chip has
to be kept on.  For bookkeeping these states, a new codec-callback is
introduced.
For the bus-controller side, a new callback pm_notify is introduced,
which can be used to turn on/off the contoller appropriately.
Note that this power-saving might cause slight click-noise at
power-on/off.  Also, it might take some time to wake up the codec, and
might even drop some tones at the very beginning.  This seems to be the
side-effect of turning off the controller chip.
This turn-off of the controller can be disabled by undefining
HDA_POWER_SAVE_RESET_CONTOLLER in hda_intel.c.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

1 files changed, 3 insertions, 3 deletions

diff --git a/sound/pci/hda/patch_sigmatel.c b/sound/pci/hda/patch_sigmatel.c
index bf5d91b63d1..4a981399abd 100644
--- a/sound/pci/hda/patch_sigmatel.c
+++ b/sound/pci/hda/patch_sigmatel.c
@@ -1946,7 +1946,7 @@ static void stac92xx_unsol_event(struct hda_codec *codec, unsigned int res)
         }
 }
 
-#ifdef CONFIG_PM
+#ifdef SND_HDA_NEEDS_RESUME
 static int stac92xx_resume(struct hda_codec *codec)
 {
         stac92xx_set_config_regs(codec);
@@ -1963,7 +1963,7 @@ static struct hda_codec_ops stac92xx_patch_ops = {
         .init = stac92xx_init,
         .free = stac92xx_free,
         .unsol_event = stac92xx_unsol_event,
-#ifdef CONFIG_PM
+#ifdef SND_HDA_NEEDS_RESUME
         .resume = stac92xx_resume,
 #endif
 };
@@ -2460,7 +2460,7 @@ static struct hda_codec_ops stac9872_patch_ops = {
         .build_pcms = stac92xx_build_pcms,
         .init = stac92xx_init,
         .free = stac92xx_free,
-#ifdef CONFIG_PM
+#ifdef SND_HDA_NEEDS_RESUME
         .resume = stac92xx_resume,
 #endif
 };