|Summary:||Wake on RTC no longer works in some kernel configurations|
|Product:||Power Management||Reporter:||Justin Maggard (jmaggard10)|
|Component:||Other||Assignee:||Rafael J. Wysocki (rjw)|
|Severity:||normal||CC:||florian, lenb, maciej.rutecki, rjw|
|Bug Depends on:|
|Bug Blocks:||7216, 27352|
|Attachments:||PM: Fix ACPI wakeup from S5 when CONFIG_PM_SLEEP is unset|
Description Justin Maggard 2011-02-23 04:37:03 UTC
Waking from S5 via RTC by writing to /sys/class/rtc/rtc0/wakealarm had been working for me for quite some time, until moving to a 2.6.37 kernel. After some digging, I found that /sys/class/rtc/rtc0/device/power/wakeup was set to disabled, while it was always set to enabled on previous kernels, and this appeared to be the main visible difference. I eventually tracked it down to to the differences in include/linux/pm_wakeup.h between 2.6.36 and 2.6.37. The rtc-cmos driver calls device_init_wakeup() during initialization, which sets the can_wakeup flag to 1. But device_init_wakeup() doesn't do anything today unless CONFIG_PM_SLEEP is set. And CONFIG_PM_SLEEP doesn't get enabled unless CONFIG_SUSPEND || CONFIG_HIBERNATION || CONFIG_XEN_SAVE_RESTORE are enabled. Seems like you shouldn't have to enable suspend to disk or suspend to RAM support in order to wake from S5, but I don't know what the proper solution is. I tried the following quick and dirty hack, and things did work after recompiling my kernel with that change; but it's obviously not a proper fix. --- linux-126.96.36.199/kernel/power/Kconfig 2011-02-17 23:44:35.000000000 +0000 +++ linux-188.8.131.52.jm/kernel/power/Kconfig 2011-02-23 03:44:02.000000000 +0000 @@ -92,7 +92,7 @@ config PM_SLEEP bool - depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE + depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE || RTC_CLASS=y default y config PM_SLEEP_ADVANCED_DEBUG
Comment 1 Rafael J. Wysocki 2011-02-23 09:23:46 UTC
Created attachment 48712 [details] PM: Fix ACPI wakeup from S5 when CONFIG_PM_SLEEP is unset Thanks for the report. Does the attached patch help (on top of 2.6.38-rc6)?
Comment 2 Justin Maggard 2011-02-23 20:08:59 UTC
Yes, it works perfectly again with your patch. Thanks for the quick response!
Comment 3 Florian Mickler 2011-02-23 21:30:12 UTC