Commit d7d5c547 authored by Mark Brown's avatar Mark Brown
Browse files

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: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 4dbfe809

sound/soc/codecs/wm8903.c

+14 −0
Original line number Diff line number Diff line
@@ -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);