linux-kernel - [PATCH v1 1/4] ASoC: codecs: tfa989x: Add switch to allow disabling amplifier

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Date:   Sun, 24 Oct 2021 10:58:37 +0200
From:   Vincent Knecht <vincent.knecht@...loo.org>
To:     stephan@...hold.net, lgirdwood@...il.com, broonie@...nel.org,
        robh+dt@...nel.org, perex@...ex.cz, tiwai@...e.com
Cc:     alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht,
        Vincent Knecht <vincent.knecht@...loo.org>
Subject: [PATCH v1 1/4] ASoC: codecs: tfa989x: Add switch to allow disabling amplifier

From: Stephan Gerhold <stephan@...hold.net>

In some configurations it may be necessary to explicitly disable
the amplifier with an ALSA mixer. An example for this is a stereo
setup with two TFA989X. If only one of them should be used (e.g.
to use it as an earpiece) the other one must be explicitly disabled.

Add a virtual "Amp Switch" to implement that. There is no register
for this (SND_SOC_NOPM) so it only prevents DAPM from activating
the amplifier. Also it is inverted (= enabled by default) for
compatibility with devices that do not need this functionality.

Signed-off-by: Stephan Gerhold <stephan@...hold.net>
Signed-off-by: Vincent Knecht <vincent.knecht@...loo.org>
---
 sound/soc/codecs/tfa989x.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/tfa989x.c b/sound/soc/codecs/tfa989x.c
index 643b45188b6f..1ae47d4f1ca7 100644
--- a/sound/soc/codecs/tfa989x.c
+++ b/sound/soc/codecs/tfa989x.c
@@ -77,13 +77,16 @@ static const struct regmap_config tfa989x_regmap = {
 
 static const char * const chsa_text[] = { "Left", "Right", /* "DSP" */ };
 static SOC_ENUM_SINGLE_DECL(chsa_enum, TFA989X_I2SREG, TFA989X_I2SREG_CHSA, chsa_text);
-static const struct snd_kcontrol_new chsa_mux = SOC_DAPM_ENUM("Amp Input", chsa_enum);
+static const struct snd_kcontrol_new
+	chsa_mux = SOC_DAPM_ENUM("Amp Input", chsa_enum),
+	amp_switch = SOC_DAPM_SINGLE("Switch", SND_SOC_NOPM, 0, 1, 1);
 
 static const struct snd_soc_dapm_widget tfa989x_dapm_widgets[] = {
 	SND_SOC_DAPM_OUTPUT("OUT"),
 	SND_SOC_DAPM_SUPPLY("POWER", TFA989X_SYS_CTRL, TFA989X_SYS_CTRL_PWDN, 1, NULL, 0),
 	SND_SOC_DAPM_OUT_DRV("AMPE", TFA989X_SYS_CTRL, TFA989X_SYS_CTRL_AMPE, 0, NULL, 0),
 
+	SND_SOC_DAPM_SWITCH("Amp", SND_SOC_NOPM, 0, 0, &amp_switch),
 	SND_SOC_DAPM_MUX("Amp Input", SND_SOC_NOPM, 0, 0, &chsa_mux),
 	SND_SOC_DAPM_AIF_IN("AIFINL", "HiFi Playback", 0, SND_SOC_NOPM, 0, 0),
 	SND_SOC_DAPM_AIF_IN("AIFINR", "HiFi Playback", 1, SND_SOC_NOPM, 0, 0),
@@ -92,7 +95,8 @@ static const struct snd_soc_dapm_widget tfa989x_dapm_widgets[] = {
 static const struct snd_soc_dapm_route tfa989x_dapm_routes[] = {
 	{"OUT", NULL, "AMPE"},
 	{"AMPE", NULL, "POWER"},
-	{"AMPE", NULL, "Amp Input"},
+	{"AMPE", NULL, "Amp"},
+	{"Amp", "Switch", "Amp Input"},
 	{"Amp Input", "Left", "AIFINL"},
 	{"Amp Input", "Right", "AIFINR"},
 };
-- 
2.31.1