[PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd_init

[PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd_init

[Jia-Ju Bai]

wbsd_init() is never called in atomic context.

The call chains ending up at wbsd_init() are:
[1] wbsd_init() <- wbsd_probe()
[2] wbsd_init() <- wbsd_pnp_probe()

wbsd_probe() is set as ".probe" in struct platform_driver.
wbsd_pnp_probe() is set as ".probe" in struct pnp_driver.
These functions are not called in atomic context.

Despite never getting called from atomic context, wbsd_init()
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@gmail.com>
---
 drivers/mmc/host/wbsd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
index 546aaf8..6224d12 100644
--- a/drivers/mmc/host/wbsd.c
+++ b/drivers/mmc/host/wbsd.c
@@ -1709,7 +1709,7 @@ static int wbsd_init(struct device *dev, int base, int irq, int dma,
 	/*
 	 * Allow device to initialise itself properly.
 	 */
-	mdelay(5);
+	usleep_range(5000, 6000);
 
 	/*
 	 * Reset the chip into a known state.
-- 
1.9.1

Re: [PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd_init

[Ulf Hansson]

On 11 April 2018 at 04:46, Jia-Ju Bai <baijiaju1990@gmail.com> wrote:
> wbsd_init() is never called in atomic context.
>
> The call chains ending up at wbsd_init() are:
> [1] wbsd_init() <- wbsd_probe()
> [2] wbsd_init() <- wbsd_pnp_probe()
>
> wbsd_probe() is set as ".probe" in struct platform_driver.
> wbsd_pnp_probe() is set as ".probe" in struct pnp_driver.
> These functions are not called in atomic context.
>
> Despite never getting called from atomic context, wbsd_init()
> 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@gmail.com>

The patch is good, however I think you should squash all three in this
series into one. For obvious reasons.

Kind regards
Uffe

> ---
>  drivers/mmc/host/wbsd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
> index 546aaf8..6224d12 100644
> --- a/drivers/mmc/host/wbsd.c
> +++ b/drivers/mmc/host/wbsd.c
> @@ -1709,7 +1709,7 @@ static int wbsd_init(struct device *dev, int base, int irq, int dma,
>         /*
>          * Allow device to initialise itself properly.
>          */
> -       mdelay(5);
> +       usleep_range(5000, 6000);
>
>         /*
>          * Reset the chip into a known state.
> --
> 1.9.1
>

Re: [PATCH 1/3] mmc: wbsd: Replace mdelay with usleep_range in wbsd_init

[Jia-Ju Bai]

On 2018/4/11 23:04, Ulf Hansson wrote:
> On 11 April 2018 at 04:46, Jia-Ju Bai <baijiaju1990@gmail.com> wrote:
>> wbsd_init() is never called in atomic context.
>>
>> The call chains ending up at wbsd_init() are:
>> [1] wbsd_init() <- wbsd_probe()
>> [2] wbsd_init() <- wbsd_pnp_probe()
>>
>> wbsd_probe() is set as ".probe" in struct platform_driver.
>> wbsd_pnp_probe() is set as ".probe" in struct pnp_driver.
>> These functions are not called in atomic context.
>>
>> Despite never getting called from atomic context, wbsd_init()
>> 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@gmail.com>
> The patch is good, however I think you should squash all three in this
> series into one. For obvious reasons.

Hello, Ulf.
Thanks for your reply and advice :)
I will follow it in my future patches.


Best wishes,
Jia-Ju Bai