[RFC 2/4] ARM: OMAP: PM: Get rid of Powerdomain book-keeping from cpuidle

[santosh.shilimkar@ti.com (Shilimkar, Santosh)]

On Fri, Jul 20, 2012 at 2:21 PM, Tero Kristo <t-kristo@ti.com> wrote:
>
> On Fri, 2012-07-20 at 13:38 +0530, Rajendra Nayak wrote:
> > On Friday 20 July 2012 12:55 PM, Shilimkar, Santosh wrote:
> > > On Fri, Jul 20, 2012 at 11:34 AM, Rajendra Nayak<rnayak@ti.com>
> > > wrote:
> > >> pwrdm_pre_transition()/pwrdm_post_transition() have always been high
> > >> latency
> > >> operations done within cpuidle to do Powerdomain level book-keeping
> > >> to know
> > >> what state transitions for different Powerdomains have been
> > >> triggered.
> > >> This is also useful to do a restore-on-demand in some cases when we
> > >> know
> > >> the context for the given Powerdomain was lost etc.
> > >>
> > >> Now that we have definitive entry/exit points (thanks to the
> > >> Powerdomain
> > >> level usecounting) for Powerdomain transitions, these book-keeping
> > >> functions
> > >> can very well be moved from within CPUidle into
> > >> pwrdm_clkdm_enable()/pwrdm_
> > >> clkdm_disable() functions.
> > >>
> > >> Also rename _pwrdm_pre/post_transition_cb() to
> > >> pwrdm_pre/post_transition()
> > >> and get rid of the original ones which iterate over all powerdomains.
> > >>
> > >> Signed-off-by: Rajendra Nayak<rnayak@ti.com>
> > >> ---
> > >>   arch/arm/mach-omap2/omap-mpuss-lowpower.c |    4 ++--
> > >>   arch/arm/mach-omap2/pm34xx.c              |    4 ++--
> > >>   arch/arm/mach-omap2/powerdomain.c         |   28
> > >> ++++++++--------------------
> > >>   arch/arm/mach-omap2/powerdomain.h         |    4 ++--
> > >>   4 files changed, 14 insertions(+), 26 deletions(-)
> > >>
> > >> diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > >> b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > >> index 13670aa..ea19439 100644
> > >> --- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > >> +++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > >> @@ -255,7 +255,7 @@ int omap4_enter_lowpower(unsigned int cpu,
> > >> unsigned int power_state)
> > >>                  return -ENXIO;
> > >>          }
> > >>
> > >> -       pwrdm_pre_transition();
> > >> +       pwrdm_cpu_idle();
> > >>
> > > Glad to see this is getting optimized.
> > > I haven't seen how "pwrdm_cpu_[idle/wakeup]()" is
> > > implemented but will those work on SMP system ?
> > > I mean OMAP4, any CPU can make this call ?
> >
> > Thats a good question. I think Tero did this so he can kick in
> > voltage transitions at the right time in idle/suspend.
> > Given that these deal with incrementing/decrementing the MPU and CORE
> > pwrdm usecounts alone, maybe on OMAP4 (SMP systems) this needs to also
> > increment/decrement the specific CPU usecounts on the CPUs these calls
> > are made.
>
> Yeah, you should keep the usecounts valid by each cpu separately calling
> these functions. My current set only sets these usecounts based on cpu0
> activity, as cpu1 is statically controlled through cpu online / offline.
> Once per-cpu cpuidle is in, these should be changed so that each
> individual cpu increases the usecounts when they are brought up,
> decrease/increase during idle, and decrease when they are brought down.
> The usecount should always reflect the number of CPUs active on MPU
> domain.
>
Sounds good to me !!

Regards
santosh