rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off()

omap_rtc_power_off() is never called in atomic context.
It calls mdelay() to busily wait, which is not necessary.
mdelay() can be replaced with msleep().

This is found by a static analysis tool named DCNS written by myself.

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

Hi,

On 30/07/2018 21:53:14+0800, Jia-Ju Bai wrote:
> omap_rtc_power_off() is never called in atomic context.
> It calls mdelay() to busily wait, which is not necessary.
> mdelay() can be replaced with msleep().
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
>  drivers/rtc/rtc-omap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 39086398833e..ef3d09525d0f 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -476,7 +476,7 @@ static void omap_rtc_power_off(void)
>  	 * power off the system. Add a 500 ms margin for external latencies
>  	 * (e.g. debounce circuits).
>  	 */
> -	mdelay(2500);
> +	msleep(2500);

I'm not sure about that one because this is a poweroff function so it
doesn't really make sense to sleep versus busy waiting (all the drivers
in power/reset use mdelay())

On Mon, Aug 27, 2018 at 10:55:17PM +0200, Alexandre Belloni wrote:
> Hi,
> 
> On 30/07/2018 21:53:14+0800, Jia-Ju Bai wrote:
> > omap_rtc_power_off() is never called in atomic context.
> > It calls mdelay() to busily wait, which is not necessary.
> > mdelay() can be replaced with msleep().
> > 
> > This is found by a static analysis tool named DCNS written by myself.
> > 
> > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> > ---
> >  drivers/rtc/rtc-omap.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> > index 39086398833e..ef3d09525d0f 100644
> > --- a/drivers/rtc/rtc-omap.c
> > +++ b/drivers/rtc/rtc-omap.c
> > @@ -476,7 +476,7 @@ static void omap_rtc_power_off(void)
> >  	 * power off the system. Add a 500 ms margin for external latencies
> >  	 * (e.g. debounce circuits).
> >  	 */
> > -	mdelay(2500);
> > +	msleep(2500);
> 
> I'm not sure about that one because this is a poweroff function so it
> doesn't really make sense to sleep versus busy waiting (all the drivers
> in power/reset use mdelay())

This power-off handler is called with interrupts disabled (as mentioned
in the function header) and must not sleep.

Johan

On 2018/8/28 16:49, Johan Hovold wrote:
> On Mon, Aug 27, 2018 at 10:55:17PM +0200, Alexandre Belloni wrote:
>> Hi,
>>
>> On 30/07/2018 21:53:14+0800, Jia-Ju Bai wrote:
>>> omap_rtc_power_off() is never called in atomic context.
>>> It calls mdelay() to busily wait, which is not necessary.
>>> mdelay() can be replaced with msleep().
>>>
>>> This is found by a static analysis tool named DCNS written by myself.
>>>
>>> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
>>> ---
>>>   drivers/rtc/rtc-omap.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>>> index 39086398833e..ef3d09525d0f 100644
>>> --- a/drivers/rtc/rtc-omap.c
>>> +++ b/drivers/rtc/rtc-omap.c
>>> @@ -476,7 +476,7 @@ static void omap_rtc_power_off(void)
>>>   	 * power off the system. Add a 500 ms margin for external latencies
>>>   	 * (e.g. debounce circuits).
>>>   	 */
>>> -	mdelay(2500);
>>> +	msleep(2500);
>> I'm not sure about that one because this is a poweroff function so it
>> doesn't really make sense to sleep versus busy waiting (all the drivers
>> in power/reset use mdelay())
> This power-off handler is called with interrupts disabled (as mentioned
> in the function header) and must not sleep.

Thanks for your reply :)

I check the code again, and find that you are right.
Sorry for my incorrect report.


Best wishes,
Jia-Ju Bai