On 04/06/2016 at 18:58:59 +0200, Gabriele Mazzotta wrote :

2016-06-04 16:46 GMT+02:00 Alexandre Belloni
[off-list ref]:

quoted

On 01/06/2016 at 17:40:14 +0200, Gabriele Mazzotta wrote :

quoted

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@localhost:~# cat /proc/driver/rtc | grep alarm_IRQ
alarm_IRQ       : no
root@localhost:~# echo +10 > /sys/class/rtc/rtc0/wakealarm
root@localhost:~# echo mem > /sys/power/state  # wait for auto-resume
root@localhost:~# echo +10 > /sys/class/rtc/rtc0/wakealarm
bash: echo: write error: Device or resource busy
root@localhost:~# 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.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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