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Date:   Fri, 15 Oct 2021 14:36:10 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 07/16] ASoC: cs42l42: Correct power-up sequence to match datasheet

The power-up sequence mandated in the datasheet is:

- VP must turn on first
- VA, VCP, VL, in any order
- VD_FILT after VL
- RESET must be asserted while VP turns on

- VD_FILT must turn off before VL
- VP must turn off last

This patch fixes the order the regulators are enabled and holds RESET
asserted around the power-up. The datasheet power-down order is the reverse
of the power-up order so this is automatically covered by listing the bulk
regulators in power-up order.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 sound/soc/codecs/cs42l42.c | 22 ++++++++++++----------
 sound/soc/codecs/cs42l42.h |  4 ++--
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index 629a0783e693..420e16563c45 100644
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -2025,22 +2025,23 @@ static int cs42l42_i2c_probe(struct i2c_client *i2c_client,
 		return ret;
 	}
 
-	ret = regulator_bulk_enable(ARRAY_SIZE(cs42l42->supplies),
-				    cs42l42->supplies);
-	if (ret != 0) {
-		dev_err(&i2c_client->dev,
-			"Failed to enable supplies: %d\n", ret);
-		return ret;
-	}
-
-	/* Reset the Device */
+	/* Hold device in reset while it powers up */
 	cs42l42->reset_gpio = devm_gpiod_get(&i2c_client->dev, "reset", GPIOD_OUT_LOW);
 	if (IS_ERR(cs42l42->reset_gpio)) {
 		ret = PTR_ERR(cs42l42->reset_gpio);
 		dev_err(&i2c_client->dev, "Failed to request reset gpio: %d\n", ret);
-		goto err_disable;
+		return ret;
 	}
 
+	ret = regulator_bulk_enable(ARRAY_SIZE(cs42l42->supplies),
+				    cs42l42->supplies);
+	if (ret != 0) {
+		dev_err(&i2c_client->dev,
+			"Failed to enable supplies: %d\n", ret);
+		return ret;
+	}
+
+	/* Release reset and wait for boot */
 	gpiod_set_value_cansleep(cs42l42->reset_gpio, 1);
 	usleep_range(CS42L42_BOOT_TIME_US, CS42L42_BOOT_TIME_US * 2);
 
@@ -2116,6 +2117,7 @@ static int cs42l42_i2c_probe(struct i2c_client *i2c_client,
 	return 0;
 
 err_disable:
+	gpiod_set_value_cansleep(cs42l42->reset_gpio, 0);
 	regulator_bulk_disable(ARRAY_SIZE(cs42l42->supplies),
 				cs42l42->supplies);
 	return ret;
diff --git a/sound/soc/codecs/cs42l42.h b/sound/soc/codecs/cs42l42.h
index 0704c902475f..2343213d0cdb 100644
--- a/sound/soc/codecs/cs42l42.h
+++ b/sound/soc/codecs/cs42l42.h
@@ -822,11 +822,11 @@
 #define CS42L42_PLL_LOCK_TIMEOUT_US	1250
 
 static const char *const cs42l42_supply_names[CS42L42_NUM_SUPPLIES] = {
-	"VA",
 	"VP",
+	"VA",
 	"VCP",
-	"VD_FILT",
 	"VL",
+	"VD_FILT",
 };
 
 struct  cs42l42_private {
-- 
2.11.0

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