linux-kernel - [PATCH v1] i2c: tegra: Ensure that device is suspended before driver is removed

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Date:   Wed, 20 Oct 2021 02:29:19 +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] i2c: tegra: Ensure that device is suspended before driver is removed

Tegra I2C device isn't guaranteed to be suspended after removal of
the driver since driver uses pm_runtime_put() that is asynchronous and
pm_runtime_disable() cancels pending power-change requests. This means
that potentially refcount of the clocks may become unbalanced after
removal of the driver. This a very minor problem which unlikely to
happen in practice and won't cause any visible problems, nevertheless
let's replace pm_runtime_disable() with pm_runtime_force_suspend() and
use pm_runtime_put_sync() which disables RPM of the device and puts it
into suspend before driver is removed.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/i2c/busses/i2c-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index c883044715f3..b3184c422826 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1700,7 +1700,7 @@ static int tegra_i2c_init_hardware(struct tegra_i2c_dev *i2c_dev)
 	else
 		ret = tegra_i2c_init(i2c_dev);

-	pm_runtime_put(i2c_dev->dev);
+	pm_runtime_put_sync(i2c_dev->dev);

 	return ret;
 }
@@ -1819,7 +1819,7 @@ static int tegra_i2c_remove(struct platform_device *pdev)
 	struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

 	i2c_del_adapter(&i2c_dev->adapter);
-	pm_runtime_disable(i2c_dev->dev);
+	pm_runtime_force_suspend(i2c_dev->dev);

 	tegra_i2c_release_dma(i2c_dev);
 	tegra_i2c_release_clocks(i2c_dev);
-- 
2.32.0