The mux put callbacks unconditionally return 0, failing to
notify the ALSA core when control values change. This prevents
userspace applications from receiving events.

Use regmap_update_bits_check() instead of regmap_update_bits()
to detect actual register changes, and return 1 when the mux value
has changed to generate proper events for userspace applications.

Fixes: f6cdf2d3445d ("ASoC: cpcap: new codec")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
 sound/soc/codecs/cpcap.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/sound/soc/codecs/cpcap.c b/sound/soc/codecs/cpcap.c
index 3eb862643b53..40b33a0acc52 100644
--- a/sound/soc/codecs/cpcap.c
+++ b/sound/soc/codecs/cpcap.c
@@ -432,6 +432,7 @@ static int cpcap_output_mux_put_enum(struct snd_kcontrol *kcontrol,
 	unsigned int mask = BIT(e->shift_l);
 	u16 reg_voice = 0x00, reg_hifi = 0x00, reg_ext = 0x00;
 	int err;
+	bool change = false;
 
 	switch (muxval) {
 	case 1:
@@ -447,22 +448,22 @@ static int cpcap_output_mux_put_enum(struct snd_kcontrol *kcontrol,
 		break;
 	}
 
-	err = regmap_update_bits(cpcap->regmap, CPCAP_REG_RXCOA,
-				 mask, reg_voice);
+	err = regmap_update_bits_check(cpcap->regmap, CPCAP_REG_RXCOA,
+				 mask, reg_voice, &change);
 	if (err)
 		return err;
-	err = regmap_update_bits(cpcap->regmap, CPCAP_REG_RXSDOA,
-				 mask, reg_hifi);
+	err = regmap_update_bits_check(cpcap->regmap, CPCAP_REG_RXSDOA,
+				 mask, reg_hifi, &change);
 	if (err)
 		return err;
-	err = regmap_update_bits(cpcap->regmap, CPCAP_REG_RXEPOA,
-				 mask, reg_ext);
+	err = regmap_update_bits_check(cpcap->regmap, CPCAP_REG_RXEPOA,
+				 mask, reg_ext, &change);
 	if (err)
 		return err;
 
 	snd_soc_dapm_mux_update_power(dapm, kcontrol, muxval, e, NULL);
 
-	return 0;
+	return change ? 1 : 0;
 }
 
 static int cpcap_input_right_mux_get_enum(struct snd_kcontrol *kcontrol,
@@ -515,6 +516,7 @@ static int cpcap_input_right_mux_put_enum(struct snd_kcontrol *kcontrol,
 	unsigned int muxval = ucontrol->value.enumerated.item[0];
 	int regval = 0, mask;
 	int err;
+	bool change = false;
 
 	mask = 0;
 	mask |= BIT(CPCAP_BIT_MIC1_MUX);
@@ -539,14 +541,14 @@ static int cpcap_input_right_mux_put_enum(struct snd_kcontrol *kcontrol,
 		break;
 	}
 
-	err = regmap_update_bits(cpcap->regmap, CPCAP_REG_TXI,
-				 mask, regval);
+	err = regmap_update_bits_check(cpcap->regmap, CPCAP_REG_TXI,
+				 mask, regval, &change);
 	if (err)
 		return err;
 
 	snd_soc_dapm_mux_update_power(dapm, kcontrol, muxval, e, NULL);
 
-	return 0;
+	return change ? 1 : 0;
 }
 
 static int cpcap_input_left_mux_get_enum(struct snd_kcontrol *kcontrol,
@@ -591,6 +593,7 @@ static int cpcap_input_left_mux_put_enum(struct snd_kcontrol *kcontrol,
 	unsigned int muxval = ucontrol->value.enumerated.item[0];
 	int regval = 0, mask;
 	int err;
+	bool change = false;
 
 	mask = 0;
 	mask |= BIT(CPCAP_BIT_MIC2_MUX);
@@ -607,14 +610,14 @@ static int cpcap_input_left_mux_put_enum(struct snd_kcontrol *kcontrol,
 		break;
 	}
 
-	err = regmap_update_bits(cpcap->regmap, CPCAP_REG_TXI,
-				 mask, regval);
+	err = regmap_update_bits_check(cpcap->regmap, CPCAP_REG_TXI,
+				 mask, regval, &change);
 	if (err)
 		return err;
 
 	snd_soc_dapm_mux_update_power(dapm, kcontrol, muxval, e, NULL);
 
-	return 0;
+	return change ? 1 : 0;
 }
 
 static const struct snd_kcontrol_new cpcap_input_left_mux =
-- 
2.50.1.windows.1