linux-kernel - Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power

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Date:   Tue, 28 Aug 2018 17:06:00 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     Johan Hovold <johan@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     j-keerthy@...com, a.zummo@...ertech.it, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in
 omap_rtc_power_off()



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@...il.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