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ALSA: hda - Tweak OLPC XO-1.5 microphone bias

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Our contacts at Conexant suggested that we reduce the external
microphone bias to 50% in order to center the input signal with
the DC input range of the codec. This is because the microphone
port is DC coupled for potential use with sensors.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Daniel Drake 2009-11-09 15:17:24 +00:00 committed by Takashi Iwai
parent 95491d902b
commit dbaccc0cca
1 changed files with 12 additions and 3 deletions
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15
sound/pci/hda/patch_conexant.c
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@ -110,6 +110,7 @@ struct conexant_spec {
unsigned int dell_automute;
unsigned int port_d_mode;
unsigned char ext_mic_bias;
};
static int conexant_playback_pcm_open(struct hda_pcm_stream *hinfo,
@ -1927,6 +1928,11 @@ static hda_nid_t cxt5066_adc_nids[3] = { 0x14, 0x15, 0x16 };
static hda_nid_t cxt5066_capsrc_nids[1] = { 0x17 };
#define CXT5066_SPDIF_OUT 0x21
/* OLPC's microphone port is DC coupled for use with external sensors,
* therefore we use a 50% mic bias in order to center the input signal with
* the DC input range of the codec. */
#define CXT5066_OLPC_EXT_MIC_BIAS PIN_VREF50
static struct hda_channel_mode cxt5066_modes[1] = {
{ 2, NULL },
};
@ -1980,9 +1986,10 @@ static int cxt5066_hp_master_sw_put(struct snd_kcontrol *kcontrol,
/* toggle input of built-in and mic jack appropriately */
static void cxt5066_automic(struct hda_codec *codec)
{
static struct hda_verb ext_mic_present[] = {
struct conexant_spec *spec = codec->spec;
struct hda_verb ext_mic_present[] = {
/* enable external mic, port B */
{0x1a, AC_VERB_SET_PIN_WIDGET_CONTROL, PIN_VREF80},
{0x1a, AC_VERB_SET_PIN_WIDGET_CONTROL, spec->ext_mic_bias},
/* switch to external mic input */
{0x17, AC_VERB_SET_CONNECT_SEL, 0},
@ -2235,7 +2242,7 @@ static struct hda_verb cxt5066_init_verbs_olpc[] = {
{0x19, AC_VERB_SET_CONNECT_SEL, 0x00}, /* DAC1 */
/* Port B: external microphone */
{0x1a, AC_VERB_SET_PIN_WIDGET_CONTROL, PIN_VREF80},
{0x1a, AC_VERB_SET_PIN_WIDGET_CONTROL, CXT5066_OLPC_EXT_MIC_BIAS},
/* Port C: internal microphone */
{0x1b, AC_VERB_SET_PIN_WIDGET_CONTROL, PIN_VREF80},
@ -2353,6 +2360,7 @@ static int patch_cxt5066(struct hda_codec *codec)
spec->input_mux = &cxt5066_capture_source;
spec->port_d_mode = PIN_HP;
spec->ext_mic_bias = PIN_VREF80;
spec->num_init_verbs = 1;
spec->init_verbs[0] = cxt5066_init_verbs;
@ -2384,6 +2392,7 @@ static int patch_cxt5066(struct hda_codec *codec)
spec->mixers[spec->num_mixers++] = cxt5066_mixer_master_olpc;
spec->mixers[spec->num_mixers++] = cxt5066_mixers;
spec->port_d_mode = 0;
spec->ext_mic_bias = CXT5066_OLPC_EXT_MIC_BIAS;
/* no S/PDIF out */
spec->multiout.dig_out_nid = 0;