On Sat, Feb 4, 2012 at 5:36 PM, Colin Cross [off-list ref] wrote:

On Sat, Feb 4, 2012 at 2:06 PM, Turquette, Mike [off-list ref] wrote:

quoted

On Sat, Feb 4, 2012 at 11:02 AM, Colin Cross [off-list ref] wrote:

quoted

What's the point of the pre_enter call? ?This seems very similar to
the prepare call that was removed in 3.2. ?Drivers can already demote

Hi Colin,

I asked Rob to re-introduce the .prepare callback (not .pre_enter).

The short version of why I requested this is so that I can experiment
with modifying wake-up latency and theshold values dynamically based
on PM QoS constraints. ?For an OMAP-specific example, I'd like to see
our C-states no longer model both MPU and CORE power domains, and
instead only model the MPU. ?Then when entering idle the PM QoS
constraints against the CORE power domain's wake-up latency can be
considered in the .prepare callback which will affect the C-state
parameters as well as program the CORE low power target state.

prepare makes sense to adjust latencies, as long as it is not used for
state demotion as well.

Latency adjustment is the plan.  State demotion is not.

Rob,

If you cook up another version of this series feel free to drop
.pre_enter.  It would be nice if you re-introduced .prepare as per our
original discussion but if that's a roadblock then you can forget that
point too and I'll take a crack at it later.

Regards,
Mike

quoted

.pre_enter isn't really right for the above case so I'm happy for it
to be dropped, but I'll probably re-introduce something like .prepare
in the future...

Regards,
Mike

quoted

the target state in their enter call. ?The only thing you do between
pre_enter and enter is trace and account for the time. ?Is there some
long call you don't want included in the idle time? ?Some
documentation would help, and you need to very clearly define the
semantics of when post_enter gets called when pre_enter or enter
return errors.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel