linux-kernel - Re: [PATCH 1/2] rtc-cmos: Clear expired alarm after resume

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Message-ID: <8f29ddb1-aaf9-9769-536e-d748eb22ed67@gmail.com>
Date:   Thu, 25 Aug 2016 16:54:18 +0200
From:   Gabriele Mazzotta <gabriele.mzt@...il.com>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        rtc-linux@...glegroups.com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        matthew.garrett@...ula.com
Subject: Re: [PATCH 1/2] rtc-cmos: Clear expired alarm after resume

On 04/06/2016 19:48, Alexandre Belloni wrote:
> On 04/06/2016 at 18:58:59 +0200, Gabriele Mazzotta wrote :
>> 2016-06-04 16:46 GMT+02:00 Alexandre Belloni
>> <alexandre.belloni@...e-electrons.com>:
>>> On 01/06/2016 at 17:40:14 +0200, Gabriele Mazzotta wrote :
>>>> If the system wakes up because of a wake alarm, the internal state
>>>> of the alarm is not updated. As consequence, the state no longer
>>>> reflects the actual state of the hardware and setting a new alarm
>>>> is not possible until the expired alarm is cleared.
>>>>
>>>
>>> I'm not completely sure to understand what is happening but could you
>>> check whether that one is solved by
>>> 2b2f5ff00f63847d95adad6289bd8b05f5983dd5 in my tree (rtc-next).
>>>
>>
>> I picked 2b2f5ff00f63847d95adad6289bd8b05f5983dd5 and applied it
>> on top of 4.7-rc1, but that didn't fix the problem.
>>
>> Let me explain the problem by showing you how I reproduce it:
>>
>> root@...alhost:~# cat /proc/driver/rtc | grep alarm_IRQ
>> alarm_IRQ       : no
>> root@...alhost:~# echo +10 > /sys/class/rtc/rtc0/wakealarm
>> root@...alhost:~# echo mem > /sys/power/state  # wait for auto-resume
>> root@...alhost:~# echo +10 > /sys/class/rtc/rtc0/wakealarm
>> bash: echo: write error: Device or resource busy
>> root@...alhost:~# cat /proc/driver/rtc | grep alarm_IRQ
>> alarm_IRQ       : yes
>>
>> To set another alarm, I have to first write 0 to wakealarm. After that
>> I can set what I want. This doesn't happen if the alarm fires while
>> the system is awake, it happens only if the system is suspended and
>> the alarm wakes it.
>>
>> I actually forgot to say that maybe this problem is not limited
>> to rtc-cmos and that maybe a general solution could be used.
>>
>> I've just looked better into what is causing this and the problem
>> seems to be caused by the fact that rtc_timer_do_work() is not
>> executed if the timer expires while the system is suspended.
>>
> 
> I doubt this is a driver independent issues as I don't get that
> behaviour on many other RTCs. I'll have a look.

Hi,

were you able to verify that no other driver is affect?

Gabriele