Tero Kristo [off-list ref] writes:

On Fri, 2012-07-20 at 13:38 +0530, Rajendra Nayak wrote:

quoted

On Friday 20 July 2012 12:55 PM, Shilimkar, Santosh wrote:

quoted

On Fri, Jul 20, 2012 at 11:34 AM, Rajendra Nayak[off-list ref]  wrote:

quoted

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<redacted>

This is excellent!   Thanks for working on this.

However, it needs a rebase against mainline though because I merged a
set of optimizations[1] to this code already that only calls pre/post
per-pwrdm.

[...]

quoted

quoted

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.

Coupled CPUidle is merging for v3.6 (hopefully OMAP support too), so
this should be addressed sooner rather than later.

Kevin

[1] Specifically, see:
commit 58f0829b7186150318c79515f0e0850c5e7a9c89
Author: Kevin Hilman [off-list ref]
Date:   Fri May 11 15:47:17 2012 -0700

    ARM: OMAP3: PM: call pre/post transition per powerdomain
    
    We only need to call the pre/post transtion methods when we know the
    power state is changing.  First, split up the pre/post transition
    calls to be per-powerdomain, and then make them conditional on whether
    the power domain is actually changing states.
    
    Reviewed-by: Santosh Shilimkar [off-list ref]
    Tested-by: Santosh Shilimkar [off-list ref]
    Tested-by: Grazvydas Ignotas [off-list ref]
    Signed-off-by: Kevin Hilman [off-list ref]