Re: [PATCH v5 2/5] tick: Add freeze timer events

From: Peter Zijlstra
Date: Thu Jul 13 2017 - 03:32:18 EST

On Fri, Jul 07, 2017 at 05:03:00PM -0700, Derek Basehore wrote:
> Adds a new feature to tick to schedule wakeups on a CPU during freeze.
> This won't fully wake up the system (devices are not resumed), but
> allow simple platform functionality to be run during freeze with
> little power impact.
> This implementation allows an idle driver to setup a timer event with
> the clock event device when entering freeze by calling
> tick_set_freeze_event. Only one caller should exist for the function.
> tick_freeze_event_expired is used to check if the timer went off when
> the CPU wakes.
> The event is cleared by tick_clear_freeze_event.

Why? What's wrong with using the RTC stuff? RTC should be able to wake
suspended systems, see RTCWAKE(8).