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ASoC: Actively manage the DC servo for WM8903

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Save a little extra power by enabling the DC servo offset correction
for the output channels only when the relevant channels are enabled.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
This commit is contained in:
Mark Brown 2009-04-22 21:03:50 +01:00
parent 4dbfe80971
commit d7d5c5476a
1 changed files with 14 additions and 0 deletions
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14
sound/soc/codecs/wm8903.c
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@ -392,14 +392,18 @@ static int wm8903_output_event(struct snd_soc_dapm_widget *w,
struct snd_soc_codec *codec = w->codec;
u16 val;
u16 reg;
u16 dcs_reg;
u16 dcs_bit;
int shift;
switch (w->reg) {
case WM8903_POWER_MANAGEMENT_2:
reg = WM8903_ANALOGUE_HP_0;
dcs_bit = 0 + w->shift;
break;
case WM8903_POWER_MANAGEMENT_3:
reg = WM8903_ANALOGUE_LINEOUT_0;
dcs_bit = 2 + w->shift;
break;
default:
BUG();
@ -439,6 +443,11 @@ static int wm8903_output_event(struct snd_soc_dapm_widget *w,
val |= (WM8903_OUTPUT_OUT << shift);
wm8903_write(codec, reg, val);
/* Enable the DC servo */
dcs_reg = wm8903_read(codec, WM8903_DC_SERVO_0);
dcs_reg |= dcs_bit;
wm8903_write(codec, WM8903_DC_SERVO_0, dcs_reg);
/* Remove the short */
val |= (WM8903_OUTPUT_SHORT << shift);
wm8903_write(codec, reg, val);
@ -451,6 +460,11 @@ static int wm8903_output_event(struct snd_soc_dapm_widget *w,
val &= ~(WM8903_OUTPUT_SHORT << shift);
wm8903_write(codec, reg, val);
/* Disable the DC servo */
dcs_reg = wm8903_read(codec, WM8903_DC_SERVO_0);
dcs_reg &= ~dcs_bit;
wm8903_write(codec, WM8903_DC_SERVO_0, dcs_reg);
/* Then disable the intermediate and output stages */
val &= ~((WM8903_OUTPUT_OUT | WM8903_OUTPUT_INT |
WM8903_OUTPUT_IN) << shift);