linux-kernel - [PATCH 1/3] thermal: armada_thermal: Replace mdelay with usleep_range in armada370_init

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Message-Id: <1523347982-29373-1-git-send-email-baijiaju1990@gmail.com>
Date:   Tue, 10 Apr 2018 16:13:02 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     rui.zhang@...el.com, edubezval@...il.com
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 1/3] thermal: armada_thermal: Replace mdelay with usleep_range in armada370_init_sensor

armada370_init_sensor() is never called in atomic context.

armada370_init_sensor() is set as ".init_sensor" in 
struct armada_thermal_data.
".init_sensor" is called armada_thermal_probe().
armada_thermal_probe() is set as ".probe" in struct platform_driver.
This function is not called in atomic context.

Despite never getting called from atomic context, armada370_init_sensor()
calls mdelay() to busily wait.
This is not necessary and can be replaced with usleep_range() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/thermal/armada_thermal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
index ae75328..807fe74 100644
--- a/drivers/thermal/armada_thermal.c
+++ b/drivers/thermal/armada_thermal.c
@@ -113,7 +113,7 @@ static void armada370_init_sensor(struct platform_device *pdev,
 	reg &= ~PMU_TDC0_START_CAL_MASK;
 	writel(reg, priv->control);

-	mdelay(10);
+	usleep_range(10000, 11000);
 }

 static void armada375_init_sensor(struct platform_device *pdev,
-- 
1.9.1