linux-kernel - [PATCH 5.6 219/254] ASoC: cs4270: pull reset GPIO low then high

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Message-Id: <20200416131353.339943848@linuxfoundation.org>
Date:   Thu, 16 Apr 2020 15:25:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mike Willard <mwillard@...tope.com>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 5.6 219/254] ASoC: cs4270: pull reset GPIO low then high

From: Mike Willard <mwillard@...tope.com>

commit ccfc531695f3a4aada042f6bdb33ac6be24e1aec upstream.

Pull the RST line low then high when initializing the driver,
in order to force a reset of the chip.
Previously, the line was not pulled low, which could result in
the chip registers not resetting to their default values on boot.

Signed-off-by: Mike Willard <mwillard@...tope.com>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20200401205454.79792-1-mwillard@izotope.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/codecs/cs4270.c |   40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

--- a/sound/soc/codecs/cs4270.c
+++ b/sound/soc/codecs/cs4270.c
@@ -137,6 +137,9 @@ struct cs4270_private {
 
 	/* power domain regulators */
 	struct regulator_bulk_data supplies[ARRAY_SIZE(supply_names)];
+
+	/* reset gpio */
+	struct gpio_desc *reset_gpio;
 };
 
 static const struct snd_soc_dapm_widget cs4270_dapm_widgets[] = {
@@ -649,6 +652,22 @@ static const struct regmap_config cs4270
 };
 
 /**
+ * cs4270_i2c_remove - deinitialize the I2C interface of the CS4270
+ * @i2c_client: the I2C client object
+ *
+ * This function puts the chip into low power mode when the i2c device
+ * is removed.
+ */
+static int cs4270_i2c_remove(struct i2c_client *i2c_client)
+{
+	struct cs4270_private *cs4270 = i2c_get_clientdata(i2c_client);
+
+	gpiod_set_value_cansleep(cs4270->reset_gpio, 0);
+
+	return 0;
+}
+
+/**
  * cs4270_i2c_probe - initialize the I2C interface of the CS4270
  * @i2c_client: the I2C client object
  * @id: the I2C device ID (ignored)
@@ -660,7 +679,6 @@ static int cs4270_i2c_probe(struct i2c_c
 	const struct i2c_device_id *id)
 {
 	struct cs4270_private *cs4270;
-	struct gpio_desc *reset_gpiod;
 	unsigned int val;
 	int ret, i;
 
@@ -679,10 +697,21 @@ static int cs4270_i2c_probe(struct i2c_c
 	if (ret < 0)
 		return ret;
 
-	reset_gpiod = devm_gpiod_get_optional(&i2c_client->dev, "reset",
-					      GPIOD_OUT_HIGH);
-	if (PTR_ERR(reset_gpiod) == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
+	/* reset the device */
+	cs4270->reset_gpio = devm_gpiod_get_optional(&i2c_client->dev, "reset",
+						     GPIOD_OUT_LOW);
+	if (IS_ERR(cs4270->reset_gpio)) {
+		dev_dbg(&i2c_client->dev, "Error getting CS4270 reset GPIO\n");
+		return PTR_ERR(cs4270->reset_gpio);
+	}
+
+	if (cs4270->reset_gpio) {
+		dev_dbg(&i2c_client->dev, "Found reset GPIO\n");
+		gpiod_set_value_cansleep(cs4270->reset_gpio, 1);
+	}
+
+	/* Sleep 500ns before i2c communications */
+	ndelay(500);
 
 	cs4270->regmap = devm_regmap_init_i2c(i2c_client, &cs4270_regmap);
 	if (IS_ERR(cs4270->regmap))
@@ -735,6 +764,7 @@ static struct i2c_driver cs4270_i2c_driv
 	},
 	.id_table = cs4270_id,
 	.probe = cs4270_i2c_probe,
+	.remove = cs4270_i2c_remove,
 };
 
 module_i2c_driver(cs4270_i2c_driver);