linux-kernel - [PATCH v3 1/5] devfreq: exynos-bus: correct clock enable sequence

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Date:   Fri, 19 Jul 2019 17:05:31 +0200
From:   k.konieczny@...tner.samsung.com
To:     k.konieczny@...tner.samsung.com
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Mark Rutland <mark.rutland@....com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: [PATCH v3 1/5] devfreq: exynos-bus: correct clock enable sequence

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 enabling sequence
of regulator and clock in exynos_bus_parse_of(). Similar change is
needed in exynos_bus_exit() where clock should be disabled first.

Signed-off-by: Kamil Konieczny <k.konieczny@...tner.samsung.com>
---
This patch is new to this series.

---
 drivers/devfreq/exynos-bus.c | 58 ++++++++++++++++++++----------------
 1 file changed, 32 insertions(+), 26 deletions(-)

diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
index 486cc5b422f1..f391044aa39d 100644
--- a/drivers/devfreq/exynos-bus.c
+++ b/drivers/devfreq/exynos-bus.c
@@ -194,11 +194,11 @@ static void exynos_bus_exit(struct device *dev)
 	if (ret < 0)
 		dev_warn(dev, "failed to disable the devfreq-event devices\n");
 
+	clk_disable_unprepare(bus->clk);
 	if (bus->regulator)
 		regulator_disable(bus->regulator);
 
 	dev_pm_opp_of_remove_table(dev);
-	clk_disable_unprepare(bus->clk);
 }
 
 /*
@@ -326,8 +326,7 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
 	return ret;
 }
 
-static int exynos_bus_parse_of(struct device_node *np,
-			      struct exynos_bus *bus)
+static int exynos_bus_parse_of(struct exynos_bus *bus)
 {
 	struct device *dev = bus->dev;
 	struct dev_pm_opp *opp;
@@ -341,36 +340,35 @@ static int exynos_bus_parse_of(struct device_node *np,
 		return PTR_ERR(bus->clk);
 	}
 
-	ret = clk_prepare_enable(bus->clk);
+	/* Get the freq and voltage from OPP table to scale the bus freq */
+	ret = dev_pm_opp_of_add_table(dev);
 	if (ret < 0) {
-		dev_err(dev, "failed to get enable clock\n");
+		dev_err(dev, "failed to get OPP table\n");
 		return ret;
 	}
 
-	/* Get the freq and voltage from OPP table to scale the bus freq */
-	ret = dev_pm_opp_of_add_table(dev);
+	ret = clk_prepare_enable(bus->clk);
 	if (ret < 0) {
-		dev_err(dev, "failed to get OPP table\n");
+		dev_err(dev, "failed to enable clock\n");
 		goto err_clk;
 	}
-
 	rate = clk_get_rate(bus->clk);
 
 	opp = devfreq_recommended_opp(dev, &rate, 0);
 	if (IS_ERR(opp)) {
 		dev_err(dev, "failed to find dev_pm_opp\n");
 		ret = PTR_ERR(opp);
-		goto err_opp;
+		goto err;
 	}
 	bus->curr_freq = dev_pm_opp_get_freq(opp);
 	dev_pm_opp_put(opp);
 
 	return 0;
 
-err_opp:
-	dev_pm_opp_of_remove_table(dev);
-err_clk:
+err:
 	clk_disable_unprepare(bus->clk);
+err_clk:
+	dev_pm_opp_of_remove_table(dev);
 
 	return ret;
 }
@@ -386,6 +384,7 @@ 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");
@@ -399,27 +398,31 @@ 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;
 	}
 
-	if (ret < 0)
-		goto err;
+	/* Parse the device-tree to get the resource information */
+	ret = exynos_bus_parse_of(bus);
+	if (ret < 0) {
+		if (!passive)
+			regulator_disable(bus->regulator);
+
+		return ret;
+	}
+
+	if (passive)
+		goto passive;
 
 	/* Initialize the struct profile and governor data for parent device */
 	profile->polling_ms = 50;
@@ -508,8 +511,11 @@ static int exynos_bus_probe(struct platform_device *pdev)
 	return 0;
 
 err:
-	dev_pm_opp_of_remove_table(dev);
 	clk_disable_unprepare(bus->clk);
+	if (!passive)
+		regulator_disable(bus->regulator);
+
+	dev_pm_opp_of_remove_table(dev);
 
 	return ret;
 }
-- 
2.22.0