[PATCH v4 1/6] Documentation: arm: define DT idle states bindings

[Sebastian Capella]

On Wed, Jun 18, 2014 at 10:36 AM, Lorenzo Pieralisi
<lorenzo.pieralisi at arm.com> wrote:
> On Fri, Jun 13, 2014 at 06:33:35PM +0100, Nicolas Pitre wrote:
>> On Fri, 13 Jun 2014, Lorenzo Pieralisi wrote:
>>
>> > On Wed, Jun 11, 2014 at 07:15:16PM +0100, Nicolas Pitre wrote:
>> > >
>> > > ...__[EXEC]__|__[PREP]--|__[ENTRY]__|__[IDLE]__|___[EXIT]_--|__[EXEC]__...
>> > >              |          |           |          |            |
>> > >              |<-- entry-latency --->|
>> > >                                                |<- exit-  ->|
>> > >                                                |  latency   |
>> > >              |<-------------- min-residency --------------->|
>> > >                         |<----- worst_wakeup_latency ------>|
>> > >
>> > > entry-latency: Worst case latency required to enter the idle state.  The
>> > > exit_latency may be guaranteed only after entry-latency has passed.
>> > >
>> > > min-residency: Minimum period, including preparation, entry and exit,
>> > > for a given power mode to be worthwhile energy wise.  It must be at
>> > > least equal to entry_latency + exit_latency.
>
> Ok, a minor tweak to the diagram above, min-residency should include
> energy costs related to idle entry and exit, but not the exit-latency
> itself, as long as the energy costs implied by exiting the state are
> factored out in the min-residency-us property.

This makes sense to me..

It includes accounting for the energy cost vs WFI of prep/entry/exit,
but timing is from the end of the previous exec, until the event is
expected to trigger.

Thanks!

Sebastian