From 05ff7e11b78f18ff6819d2c260b7bcc7da0c8f46 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 22 Jul 2009 12:39:24 +0200 Subject: 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 --- sound/pci/hda/hda_codec.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'sound/pci/hda/hda_codec.c') diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c index d686f4fcd78..3ecb45ddadf 100644 --- a/sound/pci/hda/hda_codec.c +++ b/sound/pci/hda/hda_codec.c @@ -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++) { -- cgit v1.2.3