* [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off()
@ 2018-07-30 13:53 Jia-Ju Bai
2018-08-27 20:55 ` Alexandre Belloni
0 siblings, 1 reply; 4+ messages in thread
From: Jia-Ju Bai @ 2018-07-30 13:53 UTC (permalink / raw)
To: a.zummo, alexandre.belloni; +Cc: linux-rtc, linux-kernel, Jia-Ju Bai
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);
}
static const struct rtc_class_ops omap_rtc_ops = {
--
2.17.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off()
2018-07-30 13:53 [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off() Jia-Ju Bai
@ 2018-08-27 20:55 ` Alexandre Belloni
2018-08-28 8:49 ` Johan Hovold
0 siblings, 1 reply; 4+ messages in thread
From: Alexandre Belloni @ 2018-08-27 20:55 UTC (permalink / raw)
To: Jia-Ju Bai, johan, j-keerthy; +Cc: a.zummo, linux-rtc, linux-kernel
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())
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off()
2018-08-27 20:55 ` Alexandre Belloni
@ 2018-08-28 8:49 ` Johan Hovold
2018-08-28 9:06 ` Jia-Ju Bai
0 siblings, 1 reply; 4+ messages in thread
From: Johan Hovold @ 2018-08-28 8:49 UTC (permalink / raw)
To: Alexandre Belloni
Cc: Jia-Ju Bai, johan, j-keerthy, a.zummo, linux-rtc, linux-kernel
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off()
2018-08-28 8:49 ` Johan Hovold
@ 2018-08-28 9:06 ` Jia-Ju Bai
0 siblings, 0 replies; 4+ messages in thread
From: Jia-Ju Bai @ 2018-08-28 9:06 UTC (permalink / raw)
To: Johan Hovold, Alexandre Belloni
Cc: j-keerthy, a.zummo, linux-rtc, linux-kernel
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
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-07-30 13:53 [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off() Jia-Ju Bai
2018-08-27 20:55 ` Alexandre Belloni
2018-08-28 8:49 ` Johan Hovold
2018-08-28 9:06 ` Jia-Ju Bai
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