linux-kernel - [PATCH 3/4] ASoC: wm8940: Mute also the speaker output

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Date:   Wed, 14 Dec 2022 13:37:42 +0100
From:   Lukasz Majewski <lukma@...x.de>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Stephen Kitt <steve@....org>
Cc:     patches@...nsource.cirrus.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, Lukasz Majewski <lukma@...x.de>
Subject: [PATCH 3/4] ASoC: wm8940: Mute also the speaker output

Without this change the BTL speaker produces some
"distortion" noise when test program
(speaker-test -t waw) is ended with ctrl+c.

As our design uses speaker outputs to drive BTL speaker,
it was necessary to also mute the speaker via the codec
internal WM8940_SPKVOL register with setting
WM8940_SPKMUTE bit.

Signed-off-by: Lukasz Majewski <lukma@...x.de>
---
 sound/soc/codecs/wm8940.c | 11 ++++++++++-
 sound/soc/codecs/wm8940.h |  3 +++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wm8940.c b/sound/soc/codecs/wm8940.c
index 094e74905df9..13cb57210b4b 100644
--- a/sound/soc/codecs/wm8940.c
+++ b/sound/soc/codecs/wm8940.c
@@ -465,9 +465,18 @@ static int wm8940_mute(struct snd_soc_dai *dai, int mute, int direction)
 {
 	struct snd_soc_component *component = dai->component;
 	u16 mute_reg = snd_soc_component_read(component, WM8940_DAC) & 0xffbf;
+	u16 spkvol_reg = snd_soc_component_read(component, WM8940_SPKVOL);
+	int ret;
 
-	if (mute)
+	spkvol_reg &= ~WM8940_SPKMUTE;
+	if (mute) {
 		mute_reg |= 0x40;
+		spkvol_reg |= WM8940_SPKMUTE;
+	}
+
+	ret = snd_soc_component_write(component, WM8940_SPKVOL, spkvol_reg);
+	if (ret)
+		return ret;
 
 	return snd_soc_component_write(component, WM8940_DAC, mute_reg);
 }
diff --git a/sound/soc/codecs/wm8940.h b/sound/soc/codecs/wm8940.h
index 0d4f53ada2e6..eb051ed29bb8 100644
--- a/sound/soc/codecs/wm8940.h
+++ b/sound/soc/codecs/wm8940.h
@@ -95,5 +95,8 @@ struct wm8940_setup_data {
 #define WM8940_OPCLKDIV_3 2
 #define WM8940_OPCLKDIV_4 3
 
+/* Bit definitions */
+#define WM8940_SPKMUTE BIT(6)
+
 #endif /* _WM8940_H */
 
-- 
2.20.1