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From:   Sameer Pujar <spujar@nvidia.com>
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        <alsa-devel@alsa-project.org>, <linux-tegra@vger.kernel.org>,
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Subject: [PATCH v3 12/16] ASoC: tegra: Fix kcontrol put callback in MVC
Date:   Thu, 18 Nov 2021 12:37:07 +0530
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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 MVC driver.

Fixes: e539891f9687 ("ASoC: tegra: Add Tegra210 based MVC driver")
Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Suggested-by: Jaroslav Kysela <perex@perex.cz>
Suggested-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/tegra/tegra210_mvc.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/sound/soc/tegra/tegra210_mvc.c b/sound/soc/tegra/tegra210_mvc.c
index b7e3170..85b1558 100644
--- a/sound/soc/tegra/tegra210_mvc.c
+++ b/sound/soc/tegra/tegra210_mvc.c
@@ -136,7 +136,7 @@ static int tegra210_mvc_put_mute(struct snd_kcontrol *kcontrol,
 	struct snd_soc_component *cmpnt = snd_soc_kcontrol_component(kcontrol);
 	struct tegra210_mvc *mvc = snd_soc_component_get_drvdata(cmpnt);
 	unsigned int value;
-	u8 mute_mask;
+	u8 new_mask, old_mask;
 	int err;
 
 	pm_runtime_get_sync(cmpnt->dev);
@@ -148,11 +148,19 @@ static int tegra210_mvc_put_mute(struct snd_kcontrol *kcontrol,
 	if (err < 0)
 		goto end;
 
-	mute_mask = ucontrol->value.integer.value[0];
+	regmap_read(mvc->regmap, TEGRA210_MVC_CTRL, &value);
+
+	old_mask = (value >> TEGRA210_MVC_MUTE_SHIFT) & TEGRA210_MUTE_MASK_EN;
+	new_mask = ucontrol->value.integer.value[0];
+
+	if (new_mask == old_mask) {
+		err = 0;
+		goto end;
+	}
 
 	err = regmap_update_bits(mvc->regmap, mc->reg,
 				 TEGRA210_MVC_MUTE_MASK,
-				 mute_mask << TEGRA210_MVC_MUTE_SHIFT);
+				 new_mask << TEGRA210_MVC_MUTE_SHIFT);
 	if (err < 0)
 		goto end;
 
@@ -195,7 +203,7 @@ static int tegra210_mvc_put_vol(struct snd_kcontrol *kcontrol,
 	unsigned int reg = mc->reg;
 	unsigned int value;
 	u8 chan;
-	int err;
+	int err, old_volume;
 
 	pm_runtime_get_sync(cmpnt->dev);
 
@@ -207,10 +215,16 @@ static int tegra210_mvc_put_vol(struct snd_kcontrol *kcontrol,
 		goto end;
 
 	chan = (reg - TEGRA210_MVC_TARGET_VOL) / REG_SIZE;
+	old_volume = mvc->volume[chan];
 
 	tegra210_mvc_conv_vol(mvc, chan,
 			      ucontrol->value.integer.value[0]);
 
+	if (mvc->volume[chan] == old_volume) {
+		err = 0;
+		goto end;
+	}
+
 	/* Configure init volume same as target volume */
 	regmap_write(mvc->regmap,
 		TEGRA210_MVC_REG_OFFSET(TEGRA210_MVC_INIT_VOL, chan),
-- 
2.7.4