[PATCH v3 14/16] ASoC: tegra: Fix kcontrol put callback in AMX

[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 AMX driver.

Fixes: 77f7df346c45 ("ASoC: tegra: Add Tegra210 based AMX 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_amx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/tegra/tegra210_amx.c b/sound/soc/tegra/tegra210_amx.c
index af9bddf..6895763 100644
--- a/sound/soc/tegra/tegra210_amx.c
+++ b/sound/soc/tegra/tegra210_amx.c
@@ -222,6 +222,9 @@ static int tegra210_amx_put_byte_map(struct snd_kcontrol *kcontrol,
 	int reg = mc->reg;
 	int value = ucontrol->value.integer.value[0];
 
+	if (value == bytes_map[reg])
+		return 0;
+
 	if (value >= 0 && value <= 255) {
 		/* Update byte map and enable slot */
 		bytes_map[reg] = value;
-- 
2.7.4