linux-kernel - [PATCH v2 15/19] PM / devfreq: tegra: Synchronize IRQ after masking it in hardware

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Date:   Mon, 15 Apr 2019 17:55:01 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH v2 15/19] PM / devfreq: tegra: Synchronize IRQ after masking it in hardware

There is no guarantee that interrupt handling isn't running in parallel,
hence it is necessary to synchronize IRQ in order to ensure that interrupt
is indeed disabled.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/devfreq/tegra-devfreq.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
index 46c61af8ca33..cfbfbe28e7bf 100644
--- a/drivers/devfreq/tegra-devfreq.c
+++ b/drivers/devfreq/tegra-devfreq.c
@@ -171,6 +171,8 @@ struct tegra_devfreq {
 	struct notifier_block	rate_change_nb;
 
 	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
+
+	int irq;
 };
 
 struct tegra_actmon_emc_ratio {
@@ -432,6 +434,8 @@ static void tegra_actmon_disable_interrupts(struct tegra_devfreq *tegra)
 	}
 
 	actmon_write_barrier(tegra);
+
+	synchronize_irq(tegra->irq);
 }
 
 static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
@@ -603,7 +607,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	struct resource *res;
 	unsigned int i;
 	unsigned long rate;
-	int irq;
 	int err;
 
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
@@ -659,18 +662,18 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		tegra_actmon_configure_device(tegra, dev);
 	}
 
+	tegra->irq = platform_get_irq(pdev, 0);
+	if (tegra->irq < 0) {
+		err = tegra->irq;
+		dev_err(&pdev->dev, "Failed to get IRQ: %d\n", err);
+		return err;
+	}
+
 	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
 		rate = clk_round_rate(tegra->emc_clock, rate);
 		dev_pm_opp_add(&pdev->dev, rate, 0);
 	}
 
-	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
-		err = irq;
-		dev_err(&pdev->dev, "Failed to get IRQ: %d\n", err);
-		goto remove_opps;
-	}
-
 	platform_set_drvdata(pdev, tegra);
 
 	err = devfreq_add_governor(&tegra_devfreq_governor);
@@ -689,10 +692,11 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		goto remove_governor;
 	}
 
-	err = request_threaded_irq(irq, NULL, actmon_thread_isr, IRQF_ONESHOT,
-				   "tegra-devfreq", tegra);
+	err = devm_request_threaded_irq(&pdev->dev, tegra->irq, NULL,
+					actmon_thread_isr, IRQF_ONESHOT,
+					"tegra-devfreq", tegra);
 	if (err) {
-		dev_err(&pdev->dev, "Interrupt request failed\n");
+		dev_err(&pdev->dev, "Interrupt request failed: %d\n", err);
 		goto remove_devfreq;
 	}
 
@@ -701,14 +705,11 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	if (err) {
 		dev_err(&pdev->dev,
 			"Failed to register rate change notifier\n");
-		goto disable_interrupt;
+		goto remove_devfreq;
 	}
 
 	return 0;
 
-disable_interrupt:
-	free_irq(irq, tegra);
-
 remove_devfreq:
 	devfreq_remove_device(tegra->devfreq);
 
@@ -727,10 +728,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 static int tegra_devfreq_remove(struct platform_device *pdev)
 {
 	struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
-	int irq = platform_get_irq(pdev, 0);
 
 	clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
-	free_irq(irq, tegra);
 
 	devfreq_remove_device(tegra->devfreq);
 	dev_pm_opp_remove_all_dynamic(&pdev->dev);
-- 
2.21.0