[PATCH] ASoC: sophgo: return 1 on volume change in cv1800b_adc_volume_set()

[kr494167@gmail.com]

From: Surendra Singh Chouhan <kr494167@gmail.com>

cv1800b_adc_volume_set() serves as the .put callback for the "Internal
I2S Capture Volume" control.

ALSA mixer control callbacks must return 1 when the register value is
modified, 0 if unchanged, or a negative error code on failure. Returning
0 unconditionally causes ALSA core to assume the value was unchanged,
suppressing SNDRV_CTL_EVENT_MASK_VALUE change notifications to userspace
sound servers (e.g. PipeWire/PulseAudio).

Fix this by comparing the new register value with the existing register
value. If unchanged, return 0; otherwise, write the updated value and
return 1.

Fixes: 4cf8752a03e6 ("ASoC: sophgo: add CV1800B internal ADC codec driver")
Signed-off-by: Surendra Singh Chouhan <kr494167@gmail.com>
---
 sound/soc/sophgo/cv1800b-sound-adc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sound/soc/sophgo/cv1800b-sound-adc.c b/sound/soc/sophgo/cv1800b-sound-adc.c
index b66761156b99..bd93e261bdd1 100644
--- a/sound/soc/sophgo/cv1800b-sound-adc.c
+++ b/sound/soc/sophgo/cv1800b-sound-adc.c
@@ -251,16 +251,22 @@ static int cv1800b_adc_volume_set(struct snd_kcontrol *kcontrol,
 
 	u32 v_left = clamp_t(u32, ucontrol->value.integer.value[0], 0, 24);
 	u32 v_right = clamp_t(u32, ucontrol->value.integer.value[1], 0, 24);
-	u32 val;
+	u32 val, old_val;
 
 	val = readl(priv->regs + CV1800B_RXADC_ANA0);
+	old_val = val;
+
 	val = u32_replace_bits(val, cv1800b_gains[v_left],
 			       REG_COMB_LEFT_VOLUME);
 	val = u32_replace_bits(val, cv1800b_gains[v_right],
 			       REG_COMB_RIGHT_VOLUME);
+
+	if (val == old_val)
+		return 0;
+
 	writel(val, priv->regs + CV1800B_RXADC_ANA0);
 
-	return 0;
+	return 1;
 }
 
 static DECLARE_TLV_DB_SCALE(cv1800b_volume_tlv, 0, 200, 0);
-- 
2.55.0