2018-04-10 08:19:01

by Jia-Ju Bai

Subject: [PATCH 3/3] thermal: armada_thermal: Replace mdelay with usleep_range in armada380_init_sensor

armada380_init_sensor() is never called in atomic context.

armada380_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, armada380_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 <[email protected]>
---
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..c289ae4 100644
--- a/drivers/thermal/armada_thermal.c
+++ b/drivers/thermal/armada_thermal.c
@@ -143,7 +143,7 @@ static void armada380_init_sensor(struct platform_device *pdev,
if (!(reg & A380_HW_RESET)) {
reg |= A380_HW_RESET;
writel(reg, priv->control);
- mdelay(10);
+ usleep_range(10000, 11000);
}
}

--
1.9.1

2018-04-27 02:15:30

by Eduardo Valentin

Subject: Re: [PATCH 3/3] thermal: armada_thermal: Replace mdelay with usleep_range in armada380_init_sensor

On Tue, Apr 10, 2018 at 04:13:28PM +0800, Jia-Ju Bai wrote:
> armada380_init_sensor() is never called in atomic context.
>
> armada380_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, armada380_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 <[email protected]>
> ---
> 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..c289ae4 100644
> --- a/drivers/thermal/armada_thermal.c
> +++ b/drivers/thermal/armada_thermal.c
> @@ -143,7 +143,7 @@ static void armada380_init_sensor(struct platform_device *pdev,
> if (!(reg & A380_HW_RESET)) {
> reg |= A380_HW_RESET;
> writel(reg, priv->control);
> - mdelay(10);
> + usleep_range(10000, 11000);

This does not apply:
checking file drivers/thermal/armada_thermal.c
Hunk #1 FAILED at 143.
1 out of 1 hunk FAILED

That mdelay() is not existing anymore.

> }
> }
>
> --
> 1.9.1
>