linux-kernel - [PATCH] ASoC: codecs: lpass-rx-macro: Fix playback quality distortion

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Message-ID: <20250901074403.137263-2-krzysztof.kozlowski@linaro.org>
Date: Mon,  1 Sep 2025 09:44:04 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Srinivas Kandagatla <srini@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
	linux-sound@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Alexey Klimov <alexey.klimov@...aro.org>
Subject: [PATCH] ASoC: codecs: lpass-rx-macro: Fix playback quality distortion

Commit bb4a0f497bc1 ("ASoC: codecs: lpass: Drop unused
AIF_INVALID first DAI identifier") removed first entry in enum with DAI
identifiers, because it looked unused.  Turns out that there is a
relation between DAI ID and "RX_MACRO RX0 MUX"-like kcontrols which use
"rx_macro_mux_text" array.  That "rx_macro_mux_text" array used first
three entries of DAI IDs enum, with value '0' being invalid.

The value passed tp "RX_MACRO RX0 MUX"-like kcontrols was used as DAI ID
and set to configure active channel count and mask, which are arrays
indexed by DAI ID.

After removal of first AIF_INVALID DAI identifier, this kcontrol was
updating wrong entries in active channel count and mask arrays which was
visible in reduced quality (distortions) during headset playback on the
Qualcomm SM8750 MTP8750 board.  It seems it also fixes recording silence
(instead of actual sound) via headset, even though that's different
macro codec.

Reported-by: Alexey Klimov <alexey.klimov@...aro.org>
Fixes: bb4a0f497bc1 ("ASoC: codecs: lpass: Drop unused AIF_INVALID first DAI identifier")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

---

Reported via IRC.
Fix for current v6.17-RC cycle.
---
 sound/soc/codecs/lpass-rx-macro.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/lpass-rx-macro.c b/sound/soc/codecs/lpass-rx-macro.c
index 238dbdb46c18..a8fc842cc94e 100644
--- a/sound/soc/codecs/lpass-rx-macro.c
+++ b/sound/soc/codecs/lpass-rx-macro.c
@@ -618,6 +618,7 @@ static struct interp_sample_rate sr_val_tbl[] = {
 	{176400, 0xB}, {352800, 0xC},
 };
 
+/* Matches also rx_macro_mux_text */
 enum {
 	RX_MACRO_AIF1_PB,
 	RX_MACRO_AIF2_PB,
@@ -722,6 +723,7 @@ static const char * const rx_int2_2_interp_mux_text[] = {
 	"ZERO", "RX INT2_2 MUX",
 };
 
+/* Order must match RX_MACRO_MAX_DAIS enum (offset by 1) */
 static const char *const rx_macro_mux_text[] = {
 	"ZERO", "AIF1_PB", "AIF2_PB", "AIF3_PB", "AIF4_PB"
 };
@@ -2474,6 +2476,7 @@ static int rx_macro_mux_put(struct snd_kcontrol *kcontrol,
 	struct soc_enum *e = (struct soc_enum *)kcontrol->private_value;
 	struct snd_soc_dapm_update *update = NULL;
 	u32 rx_port_value = ucontrol->value.enumerated.item[0];
+	unsigned int dai_id;
 	u32 aif_rst;
 	struct rx_macro *rx = snd_soc_component_get_drvdata(component);
 
@@ -2490,19 +2493,24 @@ static int rx_macro_mux_put(struct snd_kcontrol *kcontrol,
 
 	switch (rx_port_value) {
 	case 0:
-		if (rx->active_ch_cnt[aif_rst]) {
-			clear_bit(widget->shift,
-				&rx->active_ch_mask[aif_rst]);
-			rx->active_ch_cnt[aif_rst]--;
+		/*
+		 * active_ch_cnt and active_ch_mask use DAI IDs (RX_MACRO_MAX_DAIS).
+		 * active_ch_cnt == 0 was tested in if() above.
+		 */
+		dai_id = aif_rst - 1;
+		if (rx->active_ch_cnt[dai_id]) {
+			clear_bit(widget->shift, &rx->active_ch_mask[dai_id]);
+			rx->active_ch_cnt[dai_id]--;
 		}
 		break;
 	case 1:
 	case 2:
 	case 3:
 	case 4:
-		set_bit(widget->shift,
-			&rx->active_ch_mask[rx_port_value]);
-		rx->active_ch_cnt[rx_port_value]++;
+		/* active_ch_cnt and active_ch_mask use DAI IDs (WSA_MACRO_MAX_DAIS). */
+		dai_id = rx_port_value - 1;
+		set_bit(widget->shift, &rx->active_ch_mask[dai_id]);
+		rx->active_ch_cnt[dai_id]++;
 		break;
 	default:
 		dev_err(component->dev,
-- 
2.48.1