Messages in this thread | | | Date | Wed, 14 Feb 2024 09:29:00 +0000 | Subject | [PATCH v3 0/2] alarmtimer: Rework the suspend flow in alarmtimer | From | Pranav Prasad <> |
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Hi!
During the driver suspend phase of kernel suspend, alarmtimer's suspend callback is invoked and it identifies the earliest next wakeup alarm and programs that into the HW real time clock (RTC). However, there is an exception to this process. If the next alarm is within the next 2 seconds, the alarmtimer driver fails to suspend. In this case, a non-trivial amount of power is spent to freeze and unfreeze all userspace processes and to suspend and resume a number of devices. In the vast majority of cases, the imminent alarm that caused the failure was likely already scheduled before suspend even started. This provides an opportunity to reduce power consumption if the suspend failure decision is made earlier in the suspend flow, before the unnecessary extra work is done.
This patch series aims to achieve a kernel suspend flow in which the check for an imminent alarm is performed early during the suspend prepare phase.
Changes in v3 from v2:
- Reversed the order of patches - Formatted variable declarations - Moved the RTC device check out of alarmtimer_get_soonest() - Reinstated the check for pending alarm in alarmtimer_suspend()
Changes in v2 from v1:
- Moved the pm_wakeup_event call to the PM notifier - Added a check for RTC device in the PM notifier
Pranav Prasad (2): alarmtimer: Add PM notifier to check early for imminent alarm alarmtimer: Create sysfs to make alarm check window configurable
kernel/time/alarmtimer.c | 164 +++++++++++++++++++++++++++++++++------ 1 file changed, 140 insertions(+), 24 deletions(-)
-- 2.43.0.687.g38aa6559b0-goog
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