[alsa-devel] [PATCH] ASoC: TWL4030: PM fix for output amplifiers

[Peter Ujfalusi]

Gain controls on outputs affect the power consumption
when the gain is set to non 0 value.
To prevent amps beeing enabled, when they are not
needed, introduce the following workaround:
Track the state of each of this type of output.
In twl4030_write only allow actual write, when the
given output is enabled, otherwise only update
the reg_cache.
The PGA event handlers on power up will write the cached
value to the chip (restoring gain, routing selection).
On power down 0 is written to the register (disabling
the amp, and also just in case clearing the routing).

Signed-off-by: Peter Ujfalusi <peter.ujfalusi at nokia.com>
---
 sound/soc/codecs/twl4030.c |   72 ++++++++++++++++++++++++++++++++++----------
 1 files changed, 56 insertions(+), 16 deletions(-)

diff --git a/sound/soc/codecs/twl4030.c b/sound/soc/codecs/twl4030.c
index 6f5d4af..bf59b8a 100644
--- a/sound/soc/codecs/twl4030.c
+++ b/sound/soc/codecs/twl4030.c
@@ -135,9 +135,11 @@ struct twl4030_priv {
 
 	unsigned int sysclk;
 
-	/* Headset output state handling */
-	unsigned int hsl_enabled;
-	unsigned int hsr_enabled;
+	/* Output (with associated amp) states */
+	u8 hsl_enabled, hsr_enabled;
+	u8 earpiece_enabled;
+	u8 predrivel_enabled, predriver_enabled;
+	u8 carkitl_enabled, carkitr_enabled;
 };
 
 /*
@@ -173,12 +175,47 @@ static inline void twl4030_write_reg_cache(struct snd_soc_codec *codec,
 static int twl4030_write(struct snd_soc_codec *codec,
 			unsigned int reg, unsigned int value)
 {
+	struct twl4030_priv *twl4030 = codec->private_data;
+	int write_to_reg = 0;
+
 	twl4030_write_reg_cache(codec, reg, value);
-	if (likely(reg < TWL4030_REG_SW_SHADOW))
-		return twl_i2c_write_u8(TWL4030_MODULE_AUDIO_VOICE, value,
-					    reg);
-	else
-		return 0;
+	if (likely(reg < TWL4030_REG_SW_SHADOW)) {
+		/* Decide if the given register can be written */
+		switch (reg) {
+		case TWL4030_REG_EAR_CTL:
+			if (twl4030->earpiece_enabled)
+				write_to_reg = 1;
+			break;
+		case TWL4030_REG_PREDL_CTL:
+			if (twl4030->predrivel_enabled)
+				write_to_reg = 1;
+			break;
+		case TWL4030_REG_PREDR_CTL:
+			if (twl4030->predriver_enabled)
+				write_to_reg = 1;
+			break;
+		case TWL4030_REG_PRECKL_CTL:
+			if (twl4030->carkitl_enabled)
+				write_to_reg = 1;
+			break;
+		case TWL4030_REG_PRECKR_CTL:
+			if (twl4030->carkitr_enabled)
+				write_to_reg = 1;
+			break;
+		case TWL4030_REG_HS_GAIN_SET:
+			if (twl4030->hsl_enabled || twl4030->hsr_enabled)
+				write_to_reg = 1;
+			break;
+		default:
+			/* All other register can be written */
+			write_to_reg = 1;
+			break;
+		}
+		if (write_to_reg)
+			return twl_i2c_write_u8(TWL4030_MODULE_AUDIO_VOICE,
+						    value, reg);
+	}
+	return 0;
 }
 
 static void twl4030_codec_enable(struct snd_soc_codec *codec, int enable)
@@ -525,26 +562,26 @@ static int micpath_event(struct snd_soc_dapm_widget *w,
  * Output PGA builder:
  * Handle the muting and unmuting of the given output (turning off the
  * amplifier associated with the output pin)
- * On mute bypass the reg_cache and mute the volume
- * On unmute: restore the register content
+ * On mute bypass the reg_cache and write 0 to the register
+ * On unmute: restore the register content from the reg_cache
  * Outputs handled in this way:  Earpiece, PreDrivL/R, CarkitL/R
  */
 #define TWL4030_OUTPUT_PGA(pin_name, reg, mask)				\
 static int pin_name##pga_event(struct snd_soc_dapm_widget *w,		\
 		struct snd_kcontrol *kcontrol, int event)		\
 {									\
-	u8 reg_val;							\
+	struct twl4030_priv *twl4030 = w->codec->private_data;		\
 									\
 	switch (event) {						\
 	case SND_SOC_DAPM_POST_PMU:					\
+		twl4030->pin_name##_enabled = 1;			\
 		twl4030_write(w->codec, reg,				\
 			twl4030_read_reg_cache(w->codec, reg));		\
 		break;							\
 	case SND_SOC_DAPM_POST_PMD:					\
-		reg_val = twl4030_read_reg_cache(w->codec, reg);	\
-		twl_i2c_write_u8(TWL4030_MODULE_AUDIO_VOICE,	\
-					reg_val & (~mask),		\
-					reg);				\
+		twl4030->pin_name##_enabled = 0;			\
+		twl_i2c_write_u8(TWL4030_MODULE_AUDIO_VOICE,		\
+					0, reg);			\
 		break;							\
 	}								\
 	return 0;							\
@@ -664,7 +701,10 @@ static void headset_ramp(struct snd_soc_codec *codec, int ramp)
 		/* Headset ramp-up according to the TRM */
 		hs_pop |= TWL4030_VMID_EN;
 		twl4030_write(codec, TWL4030_REG_HS_POPN_SET, hs_pop);
-		twl4030_write(codec, TWL4030_REG_HS_GAIN_SET, hs_gain);
+		/* Actually write to the register */
+		twl_i2c_write_u8(TWL4030_MODULE_AUDIO_VOICE,
+					hs_gain,
+					TWL4030_REG_HS_GAIN_SET);
 		hs_pop |= TWL4030_RAMP_EN;
 		twl4030_write(codec, TWL4030_REG_HS_POPN_SET, hs_pop);
 		/* Wait ramp delay time + 1, so the VMID can settle */
-- 
1.7.0.2