linux-kernel - [PATCH v1 3/3] i2c: tegra: Fix suspending in active runtime PM state

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Date:   Fri, 13 Dec 2019 02:34:28 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 3/3] i2c: tegra: Fix suspending in active runtime PM state

I noticed that sometime I2C clock is kept enabled during suspend-resume.
This happens because runtime PM defers dynamic suspension and thus it may
happen that runtime PM is in active state when system enters into suspend.
In particular I2C controller that is used for CPU's DVFS is often kept ON
during suspend because CPU's voltage scaling happens quite often.

Note: we marked runtime PM as IRQ-safe during the driver's probe in the
"Support atomic transfers" patch, thus it's okay to enforce runtime PM
suspend/resume in the NOIRQ phase which is used for the system-level
suspend/resume of the driver.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/i2c/busses/i2c-tegra.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index b3ecdd87e91f..d309a314f4d6 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1790,9 +1790,14 @@ static int tegra_i2c_remove(struct platform_device *pdev)
 static int __maybe_unused tegra_i2c_suspend(struct device *dev)
 {
 	struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
+	int err;

 	i2c_mark_adapter_suspended(&i2c_dev->adapter);

+	err = pm_runtime_force_suspend(dev);
+	if (err < 0)
+		return err;
+
 	return 0;
 }

@@ -1813,6 +1818,10 @@ static int __maybe_unused tegra_i2c_resume(struct device *dev)
 	if (err)
 		return err;

+	err = pm_runtime_force_resume(dev);
+	if (err < 0)
+		return err;
+
 	i2c_mark_adapter_resumed(&i2c_dev->adapter);

 	return 0;
-- 
2.24.0