[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>

6 files changed, 315 insertions, 39 deletions

diff --git a/include/sound/ac97_codec.h b/include/sound/ac97_codec.h
index 758f8bf133c7..4c43521cc493 100644
--- a/include/sound/ac97_codec.h
+++ b/include/sound/ac97_codec.h
@@ -27,6 +27,7 @@
 
 #include <linux/bitops.h>
 #include <linux/device.h>
+#include <linux/workqueue.h>
 #include "pcm.h"
 #include "control.h"
 #include "info.h"
@@ -140,6 +141,20 @@
 #define AC97_GP_DRSS_1011       0x0000  /* LR(C) 10+11(+12) */
 #define AC97_GP_DRSS_78         0x0400  /* LR 7+8 */
 
+/* powerdown bits */
+#define AC97_PD_ADC_STATUS      0x0001  /* ADC status (RO) */
+#define AC97_PD_DAC_STATUS      0x0002  /* DAC status (RO) */
+#define AC97_PD_MIXER_STATUS    0x0004  /* Analog mixer status (RO) */
+#define AC97_PD_VREF_STATUS     0x0008  /* Vref status (RO) */
+#define AC97_PD_PR0             0x0100  /* Power down PCM ADCs and input MUX */
+#define AC97_PD_PR1             0x0200  /* Power down PCM front DAC */
+#define AC97_PD_PR2             0x0400  /* Power down Mixer (Vref still on) */
+#define AC97_PD_PR3             0x0800  /* Power down Mixer (Vref off) */
+#define AC97_PD_PR4             0x1000  /* Power down AC-Link */
+#define AC97_PD_PR5             0x2000  /* Disable internal clock usage */
+#define AC97_PD_PR6             0x4000  /* Headphone amplifier */
+#define AC97_PD_EAPD            0x8000  /* External Amplifer Power Down (EAPD) */
+
 /* extended audio ID bit defines */
 #define AC97_EI_VRA             0x0001  /* Variable bit rate supported */
 #define AC97_EI_DRA             0x0002  /* Double rate supported */
@@ -359,6 +374,7 @@
 #define AC97_SCAP_INV_EAPD      (1<<7)  /* inverted EAPD */
 #define AC97_SCAP_DETECT_BY_VENDOR (1<<8) /* use vendor registers for read tests */
 #define AC97_SCAP_NO_SPDIF      (1<<9)  /* don't build SPDIF controls */
+#define AC97_SCAP_EAPD_LED      (1<<10) /* EAPD as mute LED */
 
 /* ac97->flags */
 #define AC97_HAS_PC_BEEP        (1<<0)  /* force PC Speaker usage */
@@ -491,6 +507,12 @@ struct snd_ac97 {
         /* jack-sharing info */
         unsigned char indep_surround;
         unsigned char channel_mode;
+
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        unsigned int power_up;  /* power states */
+        struct workqueue_struct *power_workq;
+        struct work_struct power_work;
+#endif
         struct device dev;
 };
 
@@ -532,6 +554,15 @@ unsigned short snd_ac97_read(struct snd_ac97 *ac97, unsigned short reg);
 void snd_ac97_write_cache(struct snd_ac97 *ac97, unsigned short reg, unsigned short value);
 int snd_ac97_update(struct snd_ac97 *ac97, unsigned short reg, unsigned short value);
 int snd_ac97_update_bits(struct snd_ac97 *ac97, unsigned short reg, unsigned short mask, unsigned short value);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+int snd_ac97_update_power(struct snd_ac97 *ac97, int reg, int powerup);
+#else
+static inline int snd_ac97_update_power(struct snd_ac97 *ac97, int reg,
+                                        int powerup)
+{
+        return 0;
+}
+#endif
 #ifdef CONFIG_PM
 void snd_ac97_suspend(struct snd_ac97 *ac97);
 void snd_ac97_resume(struct snd_ac97 *ac97);
@@ -583,6 +614,7 @@ struct ac97_pcm {
                      copy_flag: 1,         /* lowlevel driver must fill all entries */
                      spdif: 1;             /* spdif pcm */
         unsigned short aslots;             /* active slots */
+        unsigned short cur_dbl;            /* current double-rate state */
         unsigned int rates;                /* available rates */
         struct {
                 unsigned short slots;      /* driver input: requested AC97 slot numbers */
diff --git a/sound/drivers/Kconfig b/sound/drivers/Kconfig
index 395c4ef52ac9..897dc2dfd7dd 100644
--- a/sound/drivers/Kconfig
+++ b/sound/drivers/Kconfig
@@ -100,4 +100,17 @@ config SND_MPU401
           To compile this driver as a module, choose M here: the module
           will be called snd-mpu401.
 
+config SND_AC97_POWER_SAVE
+        bool "AC97 Power-Saving Mode"
+        depends on SND_AC97_CODEC && EXPERIMENTAL
+        default n
+        help
+          Say Y here to enable the aggressive power-saving support of
+          AC97 codecs.  In this mode, the power-mode is dynamically
+          controlled at each open/close.
+
+          The mode is activated by passing power_save=1 option to
+          snd-ac97-codec driver.  You can toggle it dynamically over
+          sysfs, too.
+
 endmenu
diff --git a/sound/pci/ac97/ac97_codec.c b/sound/pci/ac97/ac97_codec.c
index b35280ca2465..f82c636e99a9 100644
--- a/sound/pci/ac97/ac97_codec.c
+++ b/sound/pci/ac97/ac97_codec.c
@@ -47,6 +47,11 @@ static int enable_loopback;
 module_param(enable_loopback, bool, 0444);
 MODULE_PARM_DESC(enable_loopback, "Enable AC97 ADC/DAC Loopback Control");
 
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+static int power_save;
+module_param(power_save, bool, 0644);
+MODULE_PARM_DESC(power_save, "Enable AC97 power-saving control");
+#endif
 /*
 
  */
@@ -187,6 +192,8 @@ static const struct ac97_codec_id snd_ac97_codec_ids[] = {
 };
 
 
+static void update_power_regs(struct snd_ac97 *ac97);
+
 /*
  *  I/O routines
  */
@@ -554,6 +561,18 @@ int snd_ac97_put_volsw(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value
         }
         err = snd_ac97_update_bits(ac97, reg, val_mask, val);
         snd_ac97_page_restore(ac97, page_save);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        /* check analog mixer power-down */
+        if ((val_mask & 0x8000) &&
+            (kcontrol->private_value & (1<<30))) {
+                if (val & 0x8000)
+                        ac97->power_up &= ~(1 << (reg>>1));
+                else
+                        ac97->power_up |= 1 << (reg>>1);
+                if (power_save)
+                        update_power_regs(ac97);
+        }
+#endif
         return err;
 }
 
@@ -962,6 +981,10 @@ static int snd_ac97_bus_dev_free(struct snd_device *device)
 static int snd_ac97_free(struct snd_ac97 *ac97)
 {
         if (ac97) {
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+                if (ac97->power_workq)
+                        destroy_workqueue(ac97->power_workq);
+#endif
                 snd_ac97_proc_done(ac97);
                 if (ac97->bus)
                         ac97->bus->codec[ac97->num] = NULL;
@@ -1117,7 +1140,9 @@ struct snd_kcontrol *snd_ac97_cnew(const struct snd_kcontrol_new *_template, str
 /*
  * create mute switch(es) for normal stereo controls
  */
-static int snd_ac97_cmute_new_stereo(struct snd_card *card, char *name, int reg, int check_stereo, struct snd_ac97 *ac97)
+static int snd_ac97_cmute_new_stereo(struct snd_card *card, char *name, int reg,
+                                     int check_stereo, int check_amix,
+                                     struct snd_ac97 *ac97)
 {
         struct snd_kcontrol *kctl;
         int err;
@@ -1137,10 +1162,14 @@ static int snd_ac97_cmute_new_stereo(struct snd_card *card, char *name, int reg,
         }
         if (mute_mask == 0x8080) {
                 struct snd_kcontrol_new tmp = AC97_DOUBLE(name, reg, 15, 7, 1, 1);
+                if (check_amix)
+                        tmp.private_value |= (1 << 30);
                 tmp.index = ac97->num;
                 kctl = snd_ctl_new1(&tmp, ac97);
         } else {
                 struct snd_kcontrol_new tmp = AC97_SINGLE(name, reg, 15, 1, 1);
+                if (check_amix)
+                        tmp.private_value |= (1 << 30);
                 tmp.index = ac97->num;
                 kctl = snd_ctl_new1(&tmp, ac97);
         }
@@ -1186,7 +1215,9 @@ static int snd_ac97_cvol_new(struct snd_card *card, char *name, int reg, unsigne
 /*
  * create a mute-switch and a volume for normal stereo/mono controls
  */
-static int snd_ac97_cmix_new_stereo(struct snd_card *card, const char *pfx, int reg, int check_stereo, struct snd_ac97 *ac97)
+static int snd_ac97_cmix_new_stereo(struct snd_card *card, const char *pfx,
+                                    int reg, int check_stereo, int check_amix,
+                                    struct snd_ac97 *ac97)
 {
         int err;
         char name[44];
@@ -1197,7 +1228,9 @@ static int snd_ac97_cmix_new_stereo(struct snd_card *card, const char *pfx, int
 
         if (snd_ac97_try_bit(ac97, reg, 15)) {
                 sprintf(name, "%s Switch", pfx);
-                if ((err = snd_ac97_cmute_new_stereo(card, name, reg, check_stereo, ac97)) < 0)
+                if ((err = snd_ac97_cmute_new_stereo(card, name, reg,
+                                                     check_stereo, check_amix,
+                                                     ac97)) < 0)
                         return err;
         }
         check_volume_resolution(ac97, reg, &lo_max, &hi_max);
@@ -1209,8 +1242,10 @@ static int snd_ac97_cmix_new_stereo(struct snd_card *card, const char *pfx, int
         return 0;
 }
 
-#define snd_ac97_cmix_new(card, pfx, reg, ac97) snd_ac97_cmix_new_stereo(card, pfx, reg, 0, ac97)
-#define snd_ac97_cmute_new(card, name, reg, ac97)       snd_ac97_cmute_new_stereo(card, name, reg, 0, ac97)
+#define snd_ac97_cmix_new(card, pfx, reg, acheck, ac97) \
+        snd_ac97_cmix_new_stereo(card, pfx, reg, 0, acheck, ac97)
+#define snd_ac97_cmute_new(card, name, reg, acheck, ac97) \
+        snd_ac97_cmute_new_stereo(card, name, reg, 0, acheck, ac97)
 
 static unsigned int snd_ac97_determine_spdif_rates(struct snd_ac97 *ac97);
 
@@ -1226,9 +1261,11 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         /* AD claims to remove this control from AD1887, although spec v2.2 does not allow this */
         if (snd_ac97_try_volume_mix(ac97, AC97_MASTER)) {
                 if (ac97->flags & AC97_HAS_NO_MASTER_VOL)
-                        err = snd_ac97_cmute_new(card, "Master Playback Switch", AC97_MASTER, ac97);
+                        err = snd_ac97_cmute_new(card, "Master Playback Switch",
+                                                 AC97_MASTER, 0, ac97);
                 else
-                        err = snd_ac97_cmix_new(card, "Master Playback", AC97_MASTER, ac97);
+                        err = snd_ac97_cmix_new(card, "Master Playback",
+                                                AC97_MASTER, 0, ac97);
                 if (err < 0)
                         return err;
         }
@@ -1265,19 +1302,23 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         if ((snd_ac97_try_volume_mix(ac97, AC97_SURROUND_MASTER)) 
                 && !(ac97->flags & AC97_AD_MULTI)) {
                 /* Surround Master (0x38) is with stereo mutes */
-                if ((err = snd_ac97_cmix_new_stereo(card, "Surround Playback", AC97_SURROUND_MASTER, 1, ac97)) < 0)
+                if ((err = snd_ac97_cmix_new_stereo(card, "Surround Playback",
+                                                    AC97_SURROUND_MASTER, 1, 0,
+                                                    ac97)) < 0)
                         return err;
         }
 
         /* build headphone controls */
         if (snd_ac97_try_volume_mix(ac97, AC97_HEADPHONE)) {
-                if ((err = snd_ac97_cmix_new(card, "Headphone Playback", AC97_HEADPHONE, ac97)) < 0)
+                if ((err = snd_ac97_cmix_new(card, "Headphone Playback",
+                                             AC97_HEADPHONE, 0, ac97)) < 0)
                         return err;
         }
         
         /* build master mono controls */
         if (snd_ac97_try_volume_mix(ac97, AC97_MASTER_MONO)) {
-                if ((err = snd_ac97_cmix_new(card, "Master Mono Playback", AC97_MASTER_MONO, ac97)) < 0)
+                if ((err = snd_ac97_cmix_new(card, "Master Mono Playback",
+                                             AC97_MASTER_MONO, 0, ac97)) < 0)
                         return err;
         }
         
@@ -1310,7 +1351,8 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         /* build Phone controls */
         if (!(ac97->flags & AC97_HAS_NO_PHONE)) {
                 if (snd_ac97_try_volume_mix(ac97, AC97_PHONE)) {
-                        if ((err = snd_ac97_cmix_new(card, "Phone Playback", AC97_PHONE, ac97)) < 0)
+                        if ((err = snd_ac97_cmix_new(card, "Phone Playback",
+                                                     AC97_PHONE, 1, ac97)) < 0)
                                 return err;
                 }
         }
@@ -1318,7 +1360,8 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         /* build MIC controls */
         if (!(ac97->flags & AC97_HAS_NO_MIC)) {
                 if (snd_ac97_try_volume_mix(ac97, AC97_MIC)) {
-                        if ((err = snd_ac97_cmix_new(card, "Mic Playback", AC97_MIC, ac97)) < 0)
+                        if ((err = snd_ac97_cmix_new(card, "Mic Playback",
+                                                     AC97_MIC, 1, ac97)) < 0)
                                 return err;
                         if ((err = snd_ctl_add(card, snd_ac97_cnew(&snd_ac97_controls_mic_boost, ac97))) < 0)
                                 return err;
@@ -1327,14 +1370,16 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
 
         /* build Line controls */
         if (snd_ac97_try_volume_mix(ac97, AC97_LINE)) {
-                if ((err = snd_ac97_cmix_new(card, "Line Playback", AC97_LINE, ac97)) < 0)
+                if ((err = snd_ac97_cmix_new(card, "Line Playback",
+                                             AC97_LINE, 1, ac97)) < 0)
                         return err;
         }
         
         /* build CD controls */
         if (!(ac97->flags & AC97_HAS_NO_CD)) {
                 if (snd_ac97_try_volume_mix(ac97, AC97_CD)) {
-                        if ((err = snd_ac97_cmix_new(card, "CD Playback", AC97_CD, ac97)) < 0)
+                        if ((err = snd_ac97_cmix_new(card, "CD Playback",
+                                                     AC97_CD, 1, ac97)) < 0)
                                 return err;
                 }
         }
@@ -1342,7 +1387,8 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         /* build Video controls */
         if (!(ac97->flags & AC97_HAS_NO_VIDEO)) {
                 if (snd_ac97_try_volume_mix(ac97, AC97_VIDEO)) {
-                        if ((err = snd_ac97_cmix_new(card, "Video Playback", AC97_VIDEO, ac97)) < 0)
+                        if ((err = snd_ac97_cmix_new(card, "Video Playback",
+                                                     AC97_VIDEO, 1, ac97)) < 0)
                                 return err;
                 }
         }
@@ -1350,7 +1396,8 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         /* build Aux controls */
         if (!(ac97->flags & AC97_HAS_NO_AUX)) {
                 if (snd_ac97_try_volume_mix(ac97, AC97_AUX)) {
-                        if ((err = snd_ac97_cmix_new(card, "Aux Playback", AC97_AUX, ac97)) < 0)
+                        if ((err = snd_ac97_cmix_new(card, "Aux Playback",
+                                                     AC97_AUX, 1, ac97)) < 0)
                                 return err;
                 }
         }
@@ -1385,9 +1432,12 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
         } else {
                 if (!(ac97->flags & AC97_HAS_NO_STD_PCM)) {
                         if (ac97->flags & AC97_HAS_NO_PCM_VOL)
-                                err = snd_ac97_cmute_new(card, "PCM Playback Switch", AC97_PCM, ac97);
+                                err = snd_ac97_cmute_new(card,
+                                                         "PCM Playback Switch",
+                                                         AC97_PCM, 0, ac97);
                         else
-                                err = snd_ac97_cmix_new(card, "PCM Playback", AC97_PCM, ac97);
+                                err = snd_ac97_cmix_new(card, "PCM Playback",
+                                                        AC97_PCM, 0, ac97);
                         if (err < 0)
                                 return err;
                 }
@@ -1398,7 +1448,9 @@ static int snd_ac97_mixer_build(struct snd_ac97 * ac97)
                 if ((err = snd_ctl_add(card, snd_ac97_cnew(&snd_ac97_control_capture_src, ac97))) < 0)
                         return err;
                 if (snd_ac97_try_bit(ac97, AC97_REC_GAIN, 15)) {
-                        if ((err = snd_ac97_cmute_new(card, "Capture Switch", AC97_REC_GAIN, ac97)) < 0)
+                        err = snd_ac97_cmute_new(card, "Capture Switch",
+                                                 AC97_REC_GAIN, 0, ac97);
+                        if (err < 0)
                                 return err;
                 }
                 if ((err = snd_ctl_add(card, snd_ac97_cnew(&snd_ac97_control_capture_vol, ac97))) < 0)
@@ -1829,6 +1881,13 @@ static int snd_ac97_dev_disconnect(struct snd_device *device)
 /* build_ops to do nothing */
 static struct snd_ac97_build_ops null_build_ops;
 
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+static void do_update_power(void *data)
+{
+        update_power_regs(data);
+}
+#endif
+
 /**
  * snd_ac97_mixer - create an Codec97 component
  * @bus: the AC97 bus which codec is attached to
@@ -1883,6 +1942,10 @@ int snd_ac97_mixer(struct snd_ac97_bus *bus, struct snd_ac97_template *template,
         bus->codec[ac97->num] = ac97;
         mutex_init(&ac97->reg_mutex);
         mutex_init(&ac97->page_mutex);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        ac97->power_workq = create_workqueue("ac97");
+        INIT_WORK(&ac97->power_work, do_update_power, ac97);
+#endif
 
 #ifdef CONFIG_PCI
         if (ac97->pci) {
@@ -2117,15 +2180,8 @@ int snd_ac97_mixer(struct snd_ac97_bus *bus, struct snd_ac97_template *template,
                         return -ENOMEM;
                 }
         }
-        /* make sure the proper powerdown bits are cleared */
-        if (ac97->scaps && ac97_is_audio(ac97)) {
-                reg = snd_ac97_read(ac97, AC97_EXTENDED_STATUS);
-                if (ac97->scaps & AC97_SCAP_SURROUND_DAC) 
-                        reg &= ~AC97_EA_PRJ;
-                if (ac97->scaps & AC97_SCAP_CENTER_LFE_DAC) 
-                        reg &= ~(AC97_EA_PRI | AC97_EA_PRK);
-                snd_ac97_write_cache(ac97, AC97_EXTENDED_STATUS, reg);
-        }
+        if (ac97_is_audio(ac97))
+                update_power_regs(ac97);
         snd_ac97_proc_init(ac97);
         if ((err = snd_device_new(card, SNDRV_DEV_CODEC, ac97, &ops)) < 0) {
                 snd_ac97_free(ac97);
@@ -2153,22 +2209,155 @@ static void snd_ac97_powerdown(struct snd_ac97 *ac97)
                 snd_ac97_write(ac97, AC97_HEADPHONE, 0x9f9f);
         }
 
-        power = ac97->regs[AC97_POWERDOWN] | 0x8000;    /* EAPD */
-        power |= 0x4000;        /* Headphone amplifier powerdown */
-        power |= 0x0300;        /* ADC & DAC powerdown */
+        /* surround, CLFE, mic powerdown */
+        power = ac97->regs[AC97_EXTENDED_STATUS];
+        if (ac97->scaps & AC97_SCAP_SURROUND_DAC)
+                power |= AC97_EA_PRJ;
+        if (ac97->scaps & AC97_SCAP_CENTER_LFE_DAC)
+                power |= AC97_EA_PRI | AC97_EA_PRK;
+        power |= AC97_EA_PRL;
+        snd_ac97_write(ac97, AC97_EXTENDED_STATUS, power);
+
+        /* powerdown external amplifier */
+        if (ac97->scaps & AC97_SCAP_INV_EAPD)
+                power = ac97->regs[AC97_POWERDOWN] & ~AC97_PD_EAPD;
+        else if (! (ac97->scaps & AC97_SCAP_EAPD_LED))
+                power = ac97->regs[AC97_POWERDOWN] | AC97_PD_EAPD;
+        power |= AC97_PD_PR6;   /* Headphone amplifier powerdown */
+        power |= AC97_PD_PR0 | AC97_PD_PR1;     /* ADC & DAC powerdown */
         snd_ac97_write(ac97, AC97_POWERDOWN, power);
         udelay(100);
-        power |= 0x0400;        /* Analog Mixer powerdown (Vref on) */
-        snd_ac97_write(ac97, AC97_POWERDOWN, power);
-        udelay(100);
-#if 0
-        /* FIXME: this causes click noises on some boards at resume */
-        power |= 0x3800;        /* AC-link powerdown, internal Clk disable */
+        power |= AC97_PD_PR2 | AC97_PD_PR3;     /* Analog Mixer powerdown */
         snd_ac97_write(ac97, AC97_POWERDOWN, power);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        if (power_save) {
+                udelay(100);
+                /* AC-link powerdown, internal Clk disable */
+                /* FIXME: this may cause click noises on some boards */
+                power |= AC97_PD_PR4 | AC97_PD_PR5;
+                snd_ac97_write(ac97, AC97_POWERDOWN, power);
+        }
 #endif
 }
 
 
+struct ac97_power_reg {
+        unsigned short reg;
+        unsigned short power_reg;
+        unsigned short mask;
+};
+
+enum { PWIDX_ADC, PWIDX_FRONT, PWIDX_CLFE, PWIDX_SURR, PWIDX_MIC, PWIDX_SIZE };
+
+static struct ac97_power_reg power_regs[PWIDX_SIZE] = {
+        [PWIDX_ADC] = { AC97_PCM_LR_ADC_RATE, AC97_POWERDOWN, AC97_PD_PR0},
+        [PWIDX_FRONT] = { AC97_PCM_FRONT_DAC_RATE, AC97_POWERDOWN, AC97_PD_PR1},
+        [PWIDX_CLFE] = { AC97_PCM_LFE_DAC_RATE, AC97_EXTENDED_STATUS,
+                         AC97_EA_PRI | AC97_EA_PRK},
+        [PWIDX_SURR] = { AC97_PCM_SURR_DAC_RATE, AC97_EXTENDED_STATUS,
+                         AC97_EA_PRJ},
+        [PWIDX_MIC] = { AC97_PCM_MIC_ADC_RATE, AC97_EXTENDED_STATUS,
+                        AC97_EA_PRL},
+};
+
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+/**
+ * snd_ac97_update_power - update the powerdown register
+ * @ac97: the codec instance
+ * @reg: the rate register, e.g. AC97_PCM_FRONT_DAC_RATE
+ * @powerup: non-zero when power up the part
+ *
+ * Update the AC97 powerdown register bits of the given part.
+ */
+int snd_ac97_update_power(struct snd_ac97 *ac97, int reg, int powerup)
+{
+        int i;
+
+        if (! ac97)
+                return 0;
+
+        if (reg) {
+                /* SPDIF requires DAC power, too */
+                if (reg == AC97_SPDIF)
+                        reg = AC97_PCM_FRONT_DAC_RATE;
+                for (i = 0; i < PWIDX_SIZE; i++) {
+                        if (power_regs[i].reg == reg) {
+                                if (powerup)
+                                        ac97->power_up |= (1 << i);
+                                else
+                                        ac97->power_up &= ~(1 << i);
+                                break;
+                        }
+                }
+        }
+
+        if (! power_save)
+                return 0;
+
+        if (! powerup && ac97->power_workq)
+                /* adjust power-down bits after two seconds delay
+                 * (for avoiding loud click noises for many (OSS) apps
+                 *  that open/close frequently)
+                 */
+                queue_delayed_work(ac97->power_workq, &ac97->power_work, HZ*2);
+        else
+                update_power_regs(ac97);
+
+        return 0;
+}
+
+EXPORT_SYMBOL(snd_ac97_update_power);
+#endif /* CONFIG_SND_AC97_POWER_SAVE */
+
+static void update_power_regs(struct snd_ac97 *ac97)
+{
+        unsigned int power_up, bits;
+        int i;
+
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        if (power_save)
+                power_up = ac97->power_up;
+        else {
+#endif
+                power_up = (1 << PWIDX_FRONT) | (1 << PWIDX_ADC);
+                power_up |= (1 << PWIDX_MIC);
+                if (ac97->scaps & AC97_SCAP_SURROUND_DAC)
+                        power_up |= (1 << PWIDX_SURR);
+                if (ac97->scaps & AC97_SCAP_CENTER_LFE_DAC)
+                        power_up |= (1 << PWIDX_CLFE);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        }
+#endif
+        if (power_up) {
+                if (ac97->regs[AC97_POWERDOWN] & AC97_PD_PR2) {
+                        /* needs power-up analog mix and vref */
+                        snd_ac97_update_bits(ac97, AC97_POWERDOWN,
+                                             AC97_PD_PR3, 0);
+                        msleep(1);
+                        snd_ac97_update_bits(ac97, AC97_POWERDOWN,
+                                             AC97_PD_PR2, 0);
+                }
+        }
+        for (i = 0; i < PWIDX_SIZE; i++) {
+                if (power_up & (1 << i))
+                        bits = 0;
+                else
+                        bits = power_regs[i].mask;
+                snd_ac97_update_bits(ac97, power_regs[i].power_reg,
+                                     power_regs[i].mask, bits);
+        }
+        if (! power_up) {
+                if (! (ac97->regs[AC97_POWERDOWN] & AC97_PD_PR2)) {
+                        /* power down analog mix and vref */
+                        snd_ac97_update_bits(ac97, AC97_POWERDOWN,
+                                             AC97_PD_PR2, AC97_PD_PR2);
+                        snd_ac97_update_bits(ac97, AC97_POWERDOWN,
+                                             AC97_PD_PR3, AC97_PD_PR3);
+                }
+        }
+}
+
+
 #ifdef CONFIG_PM
 /**
  * snd_ac97_suspend - General suspend function for AC97 codec
@@ -2484,6 +2673,7 @@ static int tune_mute_led(struct snd_ac97 *ac97)
         msw->put = master_mute_sw_put;
         snd_ac97_remove_ctl(ac97, "External Amplifier", NULL);
         snd_ac97_update_bits(ac97, AC97_POWERDOWN, 0x8000, 0x8000); /* mute LED on */
+        ac97->scaps |= AC97_SCAP_EAPD_LED;
         return 0;
 }
 
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;
 }
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 6874263f1681..72dbaedcbdf5 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -2251,6 +2251,16 @@ static int snd_intel8x0_ich_chip_init(struct intel8x0 *chip, int probing)
         /* ACLink on, 2 channels */
         cnt = igetdword(chip, ICHREG(GLOB_CNT));
         cnt &= ~(ICH_ACLINK | ICH_PCM_246_MASK);
+#ifdef CONFIG_SND_AC97_POWER_SAVE
+        /* do cold reset - the full ac97 powerdown may leave the controller
+         * in a warm state but actually it cannot communicate with the codec.
+         */
+        iputdword(chip, ICHREG(GLOB_CNT), cnt & ~ICH_AC97COLD);
+        cnt = igetdword(chip, ICHREG(GLOB_CNT));
+        udelay(10);
+        iputdword(chip, ICHREG(GLOB_CNT), cnt | ICH_AC97COLD);
+        msleep(1);
+#else
         /* finish cold or do warm reset */
         cnt |= (cnt & ICH_AC97COLD) == 0 ? ICH_AC97COLD : ICH_AC97WARM;
         iputdword(chip, ICHREG(GLOB_CNT), cnt);
@@ -2265,6 +2275,7 @@ static int snd_intel8x0_ich_chip_init(struct intel8x0 *chip, int probing)
         return -EIO;
 
       __ok:
+#endif
         if (probing) {
                 /* wait for any codec ready status.
                  * Once it becomes ready it should remain ready
@@ -2485,7 +2496,7 @@ static int intel8x0_resume(struct pci_dev *pci)
                     card->shortname, chip);
         chip->irq = pci->irq;
         synchronize_irq(chip->irq);
-        snd_intel8x0_chip_init(chip, 1);
+        snd_intel8x0_chip_init(chip, 0);
 
         /* re-initialize mixer stuff */
         if (chip->device_type == DEVICE_INTEL_ICH4) {
@@ -2615,6 +2626,7 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
                 /* not 48000Hz, tuning the clock.. */
                 chip->ac97_bus->clock = (chip->ac97_bus->clock * 48000) / pos;
         printk(KERN_INFO "intel8x0: clocking to %d\n", chip->ac97_bus->clock);
+        snd_ac97_update_power(chip->ac97[0], AC97_PCM_FRONT_DAC_RATE, 0);
 }
 
 #ifdef CONFIG_PROC_FS
diff --git a/sound/pci/via82xx.c b/sound/pci/via82xx.c
index 08da9234efb3..2c23a665c3e3 100644
--- a/sound/pci/via82xx.c
+++ b/sound/pci/via82xx.c
@@ -1277,7 +1277,18 @@ static int snd_via82xx_pcm_close(struct snd_pcm_substream *substream)
         if (! ratep->used)
                 ratep->rate = 0;
         spin_unlock_irq(&ratep->lock);
-
+        if (! ratep->rate) {
+                if (! viadev->direction) {
+                        snd_ac97_update_power(chip->ac97,
+                                              AC97_PCM_FRONT_DAC_RATE, 0);
+                        snd_ac97_update_power(chip->ac97,
+                                              AC97_PCM_SURR_DAC_RATE, 0);
+                        snd_ac97_update_power(chip->ac97,
+                                              AC97_PCM_LFE_DAC_RATE, 0);
+                } else
+                        snd_ac97_update_power(chip->ac97,
+                                              AC97_PCM_LR_ADC_RATE, 0);
+        }
         viadev->substream = NULL;
         return 0;
 }