[ALSA] Add experimental support of aggressive AC97 power-saving mode

Added CONFIG_SND_AC97_POWER_SAVE kernel config to enable the support
of aggressive AC97 power-saving mode.  In this mode, the AC97
powerdown register bits are dynamically controlled at each open/close
of PCM streams.
The mode is activated via power_save option for snd-ac97-codec
driver.  As default it's off.  It can be turned on/off on the fly
via sysfs, too.

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

1 files changed, 18 insertions, 0 deletions

diff --git a/sound/pci/ac97/ac97_pcm.c b/sound/pci/ac97/ac97_pcm.c
index f684aa2c0067..3758d07182f8 100644
--- a/sound/pci/ac97/ac97_pcm.c
+++ b/sound/pci/ac97/ac97_pcm.c
@@ -269,6 +269,7 @@ int snd_ac97_set_rate(struct snd_ac97 *ac97, int reg, unsigned int rate)
                         return -EINVAL;
         }
 
+        snd_ac97_update_power(ac97, reg, 1);
         switch (reg) {
         case AC97_PCM_MIC_ADC_RATE:
                 if ((ac97->regs[AC97_EXTENDED_STATUS] & AC97_EA_VRM) == 0)      /* MIC VRA */
@@ -606,6 +607,7 @@ int snd_ac97_pcm_open(struct ac97_pcm *pcm, unsigned int rate,
                         goto error;
                 }
         }
+        pcm->cur_dbl = r;
         spin_unlock_irq(&pcm->bus->bus_lock);
         for (i = 3; i < 12; i++) {
                 if (!(slots & (1 << i)))
@@ -651,6 +653,21 @@ int snd_ac97_pcm_close(struct ac97_pcm *pcm)
         unsigned short slots = pcm->aslots;
         int i, cidx;
 
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        int r = pcm->cur_dbl;
+        for (i = 3; i < 12; i++) {
+                if (!(slots & (1 << i)))
+                        continue;
+                for (cidx = 0; cidx < 4; cidx++) {
+                        if (pcm->r[r].rslots[cidx] & (1 << i)) {
+                                int reg = get_slot_reg(pcm, cidx, i, r);
+                                snd_ac97_update_power(pcm->r[r].codec[cidx],
+                                                      reg, 0);
+                        }
+                }
+        }
+#endif
+
         bus = pcm->bus;
         spin_lock_irq(&pcm->bus->bus_lock);
         for (i = 3; i < 12; i++) {
@@ -660,6 +677,7 @@ int snd_ac97_pcm_close(struct ac97_pcm *pcm)
                         bus->used_slots[pcm->stream][cidx] &= ~(1 << i);
         }
         pcm->aslots = 0;
+        pcm->cur_dbl = 0;
         spin_unlock_irq(&pcm->bus->bus_lock);
         return 0;
 }