[PATCH v3 15/16] ASoC: tegra: Fix kcontrol put callback in ADX

[Sameer Pujar]

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 ADX driver.

Fixes: a99ab6f395a9 ("ASoC: tegra: Add Tegra210 based ADX driver")
Signed-off-by: Sameer Pujar <spujar at nvidia.com>
Suggested-by: Jaroslav Kysela <perex at perex.cz>
Suggested-by: Mark Brown <broonie at kernel.org>
---
 sound/soc/tegra/tegra210_adx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/tegra/tegra210_adx.c b/sound/soc/tegra/tegra210_adx.c
index d7c7849..933c450 100644
--- a/sound/soc/tegra/tegra210_adx.c
+++ b/sound/soc/tegra/tegra210_adx.c
@@ -193,6 +193,9 @@ static int tegra210_adx_put_byte_map(struct snd_kcontrol *kcontrol,
 	struct soc_mixer_control *mc =
 		(struct soc_mixer_control *)kcontrol->private_value;;
 
+	if (value == bytes_map[mc->reg])
+		return 0;
+
 	if (value >= 0 && value <= 255) {
 		/* update byte map and enable slot */
 		bytes_map[mc->reg] = value;
-- 
2.7.4