[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>
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 6874263..72dbaed 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -2251,6 +2251,16 @@
/* 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 @@
return -EIO;
__ok:
+#endif
if (probing) {
/* wait for any codec ready status.
* Once it becomes ready it should remain ready
@@ -2485,7 +2496,7 @@
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 @@
/* 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