ASoC: tegra: Fix kcontrol put callback in Mixer

The kcontrol put callback is expected to return 1 when there is change
in HW or when the update is acknowledged by driver. This would ensure
that change notifications are sent to subscribed applications. Filter
out duplicate updates in Mixer driver.

Fixes: 05bb3d5e ("ASoC: tegra: Add Tegra210 based Mixer driver")
Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Suggested-by: Jaroslav Kysela <perex@perex.cz>
Suggested-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/1637219231-406-17-git-send-email-spujar@nvidia.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/tegra/tegra210_mixer.c

@@ -192,24 +192,24 @@ static int tegra210_mixer_get_gain(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static int tegra210_mixer_put_gain(struct snd_kcontrol *kcontrol,
-				   struct snd_ctl_elem_value *ucontrol)
+static int tegra210_mixer_apply_gain(struct snd_kcontrol *kcontrol,
+				     struct snd_ctl_elem_value *ucontrol,
+				     bool instant_gain)
 {
 	struct soc_mixer_control *mc =
 		(struct soc_mixer_control *)kcontrol->private_value;
 	struct snd_soc_component *cmpnt = snd_soc_kcontrol_component(kcontrol);
 	struct tegra210_mixer *mixer = snd_soc_component_get_drvdata(cmpnt);
 	unsigned int reg = mc->reg, id;
-	bool instant_gain = false;
 	int err;
 
-	if (strstr(kcontrol->id.name, "Instant Gain Volume"))
-		instant_gain = true;
-
 	/* Save gain value for specific MIXER input */
 	id = (reg - TEGRA210_MIXER_GAIN_CFG_RAM_ADDR_0) /
 	     TEGRA210_MIXER_GAIN_CFG_RAM_ADDR_STRIDE;
 
+	if (mixer->gain_value[id] == ucontrol->value.integer.value[0])
+		return 0;
+
 	mixer->gain_value[id] = ucontrol->value.integer.value[0];
 
 	err = tegra210_mixer_configure_gain(cmpnt, id, instant_gain);
@@ -221,6 +221,18 @@ static int tegra210_mixer_put_gain(struct snd_kcontrol *kcontrol,
 	return 1;
 }
 
+static int tegra210_mixer_put_gain(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	return tegra210_mixer_apply_gain(kcontrol, ucontrol, false);
+}
+
+static int tegra210_mixer_put_instant_gain(struct snd_kcontrol *kcontrol,
+					   struct snd_ctl_elem_value *ucontrol)
+{
+	return tegra210_mixer_apply_gain(kcontrol, ucontrol, true);
+}
+
 static int tegra210_mixer_set_audio_cif(struct tegra210_mixer *mixer,
 					struct snd_pcm_hw_params *params,
 					unsigned int reg,
@@ -388,7 +400,7 @@ ADDER_CTRL_DECL(adder5, TEGRA210_MIXER_TX5_ADDER_CONFIG);
 	SOC_SINGLE_EXT("RX" #id " Instant Gain Volume",		\
 		       MIXER_GAIN_CFG_RAM_ADDR((id) - 1), 0,	\
 		       0x20000, 0, tegra210_mixer_get_gain,	\
-		       tegra210_mixer_put_gain),
+		       tegra210_mixer_put_instant_gain),
 
 /* Volume controls for all MIXER inputs */
 static const struct snd_kcontrol_new tegra210_mixer_gain_ctls[] = {