Gitweb: http://git.kernel.org/linus/d7d5c5476a12333a33b7a14ebb10eccc729c01cb
Commit: d7d5c5476a12333a33b7a14ebb10eccc729c01cb
Parent: 4dbfe8097157fde1f8054f48f991ea45833852cd
Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
AuthorDate: Wed Apr 22 21:03:50 2009 +0100
Committer: Mark Brown <broonie@opensource.wolfsonmicro.com>
CommitDate: Wed Apr 22 21:37:36 2009 +0100
ASoC: Actively manage the DC servo for WM8903
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>
---
sound/soc/codecs/wm8903.c | 14 ++++++++++++++
1 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/sound/soc/codecs/wm8903.c b/sound/soc/codecs/wm8903.c
index de0a585..0bab5c6 100644
--- a/sound/soc/codecs/wm8903.c
+++ b/sound/soc/codecs/wm8903.c
@@ -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);
--
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