On Tuesday, November 15, 2016 02:20:21 PM Sudeep Holla wrote: > Hi Rafael, > > On 10/11/16 14:24, Sudeep Holla wrote: > > enter_freeze() callback is expected atleast to do the same as enter() > > but it has to guarantee that interrupts aren't enabled at any point > > in its execution, as the tick is frozen. > > > > CPUs execute ->enter_freeze with the local tick or entire timekeeping > > suspended, so it must not re-enable interrupts at any point (even > > temporarily) or attempt to change states of clock event devices. > > > > It will be called when the system goes to suspend-to-idle and will > > reduce power usage because CPUs won't be awaken for unnecessary IRQs > > (i.e. woken up only on IRQs from "wakeup sources") > > > > We can reuse the same code for both the enter() and enter_freeze() > > callbacks as along as they don't re-enable interrupts. Only "coupled" > > cpuidle mechanism enables interrupts and doing that with timekeeping > > suspended is generally not safe. > > > > Since this generic DT based idle driver doesn't support "coupled" > > states, it is safe to assume that the interrupts are not re-enabled. > > > > This patch assign enter_freeze to same as enter callback function which > > helps to save power without any intermittent spurious wakeups from > > suspend-to-idle. > > > > Cc: "Rafael J. Wysocki" <[email protected]> > > Signed-off-by: Sudeep Holla <[email protected]> > > --- > > drivers/cpuidle/dt_idle_states.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > v1->v2: > > - Dropped checking and using only states with CPUIDLE_FLAG_TIMER_STOP > > enabled. > > > > Can you pick up this patch directly if there are no concerns ?
There were none, so it's been queued up for 4.10. Thanks, Rafael
