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ALSA: hda - Reduce click noise at power-saving

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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>
This commit is contained in:
Takashi Iwai
2009-07-22 12:39:24 +02:00
parent 05e870d29a
commit 05ff7e11b7
2 changed files with 21 additions and 2 deletions
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9
sound/pci/hda/hda_codec.c
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@@ -2367,9 +2367,14 @@ static void hda_set_power_state(struct hda_codec *codec, hda_nid_t fg,
hda_nid_t nid;
int i;
snd_hda_codec_write(codec, fg, 0, AC_VERB_SET_POWER_STATE,
/* this delay seems necessary to avoid click noise at power-down */
if (power_state == AC_PWRST_D3)
msleep(100);
snd_hda_codec_read(codec, fg, 0, AC_VERB_SET_POWER_STATE,
power_state);
msleep(10); /* partial workaround for "azx_get_response timeout" */
/* partial workaround for "azx_get_response timeout" */
if (power_state == AC_PWRST_D0)
msleep(10);
nid = codec->start_nid;
for (i = 0; i < codec->num_nodes; i++, nid++) {