linux-kernel - [PATCH 4.9 070/129] PM / devfreq: exynos-bus: Correct clock enable sequence

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Date:   Thu,  3 Oct 2019 17:53:13 +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,
        Kamil Konieczny <k.konieczny@...tner.samsung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 070/129] PM / devfreq: exynos-bus: Correct clock enable sequence

From: Kamil Konieczny <k.konieczny@...tner.samsung.com>

[ Upstream commit 2c2b20e0da89c76759ee28c6824413ab2fa3bfc6 ]

Regulators should be enabled before clocks to avoid h/w hang. This
require change in exynos_bus_probe() to move exynos_bus_parse_of()
after exynos_bus_parent_parse_of() and change in error handling.
Similar change is needed in exynos_bus_exit() where clock should be
disabled before regulators.

Signed-off-by: Kamil Konieczny <k.konieczny@...tner.samsung.com>
Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/devfreq/exynos-bus.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
index 1b21bb60e7975..2c8f41fbe94fb 100644
--- a/drivers/devfreq/exynos-bus.c
+++ b/drivers/devfreq/exynos-bus.c
@@ -198,11 +198,10 @@ static void exynos_bus_exit(struct device *dev)
 	if (ret < 0)
 		dev_warn(dev, "failed to disable the devfreq-event devices\n");
 
-	if (bus->regulator)
-		regulator_disable(bus->regulator);
-
 	dev_pm_opp_of_remove_table(dev);
 	clk_disable_unprepare(bus->clk);
+	if (bus->regulator)
+		regulator_disable(bus->regulator);
 }
 
 /*
@@ -391,6 +390,7 @@ static int exynos_bus_probe(struct platform_device *pdev)
 	struct exynos_bus *bus;
 	int ret, max_state;
 	unsigned long min_freq, max_freq;
+	bool passive = false;
 
 	if (!np) {
 		dev_err(dev, "failed to find devicetree node\n");
@@ -404,27 +404,27 @@ static int exynos_bus_probe(struct platform_device *pdev)
 	bus->dev = &pdev->dev;
 	platform_set_drvdata(pdev, bus);
 
-	/* Parse the device-tree to get the resource information */
-	ret = exynos_bus_parse_of(np, bus);
-	if (ret < 0)
-		return ret;
-
 	profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
-	if (!profile) {
-		ret = -ENOMEM;
-		goto err;
-	}
+	if (!profile)
+		return -ENOMEM;
 
 	node = of_parse_phandle(dev->of_node, "devfreq", 0);
 	if (node) {
 		of_node_put(node);
-		goto passive;
+		passive = true;
 	} else {
 		ret = exynos_bus_parent_parse_of(np, bus);
+		if (ret < 0)
+			return ret;
 	}
 
+	/* Parse the device-tree to get the resource information */
+	ret = exynos_bus_parse_of(np, bus);
 	if (ret < 0)
-		goto err;
+		goto err_reg;
+
+	if (passive)
+		goto passive;
 
 	/* Initialize the struct profile and governor data for parent device */
 	profile->polling_ms = 50;
@@ -514,6 +514,9 @@ static int exynos_bus_probe(struct platform_device *pdev)
 err:
 	dev_pm_opp_of_remove_table(dev);
 	clk_disable_unprepare(bus->clk);
+err_reg:
+	if (!passive)
+		regulator_disable(bus->regulator);
 
 	return ret;
 }
-- 
2.20.1