ASoC: sgtl5000: Fix noise on shutdown/remove

Put the SGTL5000 in a silent/safe state on shutdown/remove, this is
required since the SGTL5000 produces a constant noise on its output
after it is configured and its clock is removed. Without this change
this is happening every time the module is unbound/removed or from
reboot till the clock is enabled again.

The issue was experienced on both a Toradex Colibri/Apalis iMX6, but can
be easily reproduced everywhere just playing something on the codec and
after that removing/unbinding the driver.

Fixes: 9b34e6cc3b ("ASoC: Add Freescale SGTL5000 codec support")
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Link: https://lore.kernel.org/r/20220624101301.441314-1-francesco.dolcini@toradex.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/sgtl5000.c

@@ -1795,6 +1795,9 @@ static int sgtl5000_i2c_remove(struct i2c_client *client)
 {
 	struct sgtl5000_priv *sgtl5000 = i2c_get_clientdata(client);
 
+	regmap_write(sgtl5000->regmap, SGTL5000_CHIP_DIG_POWER, SGTL5000_DIG_POWER_DEFAULT);
+	regmap_write(sgtl5000->regmap, SGTL5000_CHIP_ANA_POWER, SGTL5000_ANA_POWER_DEFAULT);
+
 	clk_disable_unprepare(sgtl5000->mclk);
 	regulator_bulk_disable(sgtl5000->num_supplies, sgtl5000->supplies);
 	regulator_bulk_free(sgtl5000->num_supplies, sgtl5000->supplies);
@@ -1802,6 +1805,11 @@ static int sgtl5000_i2c_remove(struct i2c_client *client)
 	return 0;
 }
 
+static void sgtl5000_i2c_shutdown(struct i2c_client *client)
+{
+	sgtl5000_i2c_remove(client);
+}
+
 static const struct i2c_device_id sgtl5000_id[] = {
 	{"sgtl5000", 0},
 	{},
@@ -1822,6 +1830,7 @@ static struct i2c_driver sgtl5000_i2c_driver = {
 	},
 	.probe_new = sgtl5000_i2c_probe,
 	.remove = sgtl5000_i2c_remove,
+	.shutdown = sgtl5000_i2c_shutdown,
 	.id_table = sgtl5000_id,
 };
 

sound/soc/codecs/sgtl5000.h

@@ -80,6 +80,7 @@
 /*
  * SGTL5000_CHIP_DIG_POWER
  */
+#define SGTL5000_DIG_POWER_DEFAULT		0x0000
 #define SGTL5000_ADC_EN				0x0040
 #define SGTL5000_DAC_EN				0x0020
 #define SGTL5000_DAP_POWERUP			0x0010