ALSA: hda - Reduce click noise at power-saving
Add some tricks to reduce the click noise at powering down to D3
in the power saving mode on STAC/IDT codecs.
The key seems to be to reset PINs before the power-down, and some
delay before entering D3. The needed delay is significantly long,
but I don't know why.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/patch_sigmatel.c b/sound/pci/hda/patch_sigmatel.c
index 41b5b3a..00c702d 100644
--- a/sound/pci/hda/patch_sigmatel.c
+++ b/sound/pci/hda/patch_sigmatel.c
@@ -4745,6 +4745,20 @@
static int stac92xx_suspend(struct hda_codec *codec, pm_message_t state)
{
struct sigmatel_spec *spec = codec->spec;
+ int i;
+ hda_nid_t nid;
+
+ /* reset each pin before powering down DAC/ADC to avoid click noise */
+ nid = codec->start_nid;
+ for (i = 0; i < codec->num_nodes; i++, nid++) {
+ unsigned int wcaps = get_wcaps(codec, nid);
+ unsigned int wid_type = (wcaps & AC_WCAP_TYPE) >>
+ AC_WCAP_TYPE_SHIFT;
+ if (wid_type == AC_WID_PIN)
+ snd_hda_codec_read(codec, nid, 0,
+ AC_VERB_SET_PIN_WIDGET_CONTROL, 0);
+ }
+
if (spec->eapd_mask)
stac_gpio_set(codec, spec->gpio_mask,
spec->gpio_dir, spec->gpio_data &
