Hi Kevin,

<snip>..

> >     if (pwrdm_read_pwrst(pwrdm) < PWRDM_POWER_ON) {
> > +           if ((pwrdm_read_pwrst(pwrdm) > state) &&
> > +                   (pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE)) {
> > +                           ret = pwrdm_set_next_pwrst(pwrdm, state);
> > +                           pwrdm_set_lowpwrstchange(pwrdm);
> > +                           pwrdm_wait_transition(pwrdm);
> > +                           pwrdm_state_switch(pwrdm);
> > +                           return ret;
>
> Personally, I'd prefer if this function flowed through better instead of
> the early return in order to emphasize the common code.
>
> Rather than the return here, can you just set the low-power state change
> bit here (and put the clkdm_wakeup + sleep_switch = 1 into the else
> clause?
>
> Or, does the next state have to be set before the low-power state change
> bit?

Yes, that sequencing is needed.

>
> Basically, what I'm getting at is this should be a single function with
> common flow.  The conditional code based on low-power state change
> should be isolated instead of having a special path.

I get your point. See if the below approach looks better.
If it looks fine, I'll do some more testing (currently only tested
on OMAP4430sdp) and repost the 2 patches.

>From 5d206ba908071edafae6c044bd3ef6ad8a9c32e7 Mon Sep 17 00:00:00 2001
From: Rajendra Nayak <[email protected]>
Date: Thu, 25 Nov 2010 14:26:51 +0530
Subject: [PATCH 1/5] OMAP4: PM: Use the low-power state change feature on
OMAP4

For pwrdm's which support LOWPOWERSTATECHANGE, do not try waking
up the domain to put it back to deeper sleep state.

Signed-off-by: Rajendra Nayak <[email protected]>
Signed-off-by: Santosh Shilimkar <[email protected]>
Acked-by: Benoit Cousson <[email protected]>
---
 arch/arm/mach-omap2/pm.c |   28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

Index: linux/arch/arm/mach-omap2/pm.c
===================================================================
--- linux.orig/arch/arm/mach-omap2/pm.c 2010-12-15 17:29:42.361228780
+0530
+++ linux/arch/arm/mach-omap2/pm.c      2010-12-15 20:19:48.321228780
+0530
@@ -89,6 +89,10 @@
        }
 }

+/* Types of sleep_switch used in omap_set_pwrdm_state */
+#define FORCEWAKEUP_SWITCH     0
+#define LOWPOWERSTATE_SWITCH   1
+
 /*
  * This sets pwrdm state (other than mpu & core. Currently only ON &
  * RET are supported. Function is assuming that clkdm doesn't have
@@ -114,9 +118,14 @@
                return ret;

        if (pwrdm_read_pwrst(pwrdm) < PWRDM_POWER_ON) {
-               omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
-               sleep_switch = 1;
-               pwrdm_wait_transition(pwrdm);
+               if ((pwrdm_read_pwrst(pwrdm) > state) &&
+                       (pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE)) {
+                       sleep_switch = LOWPOWERSTATE_SWITCH;
+               } else {
+                       omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
+                       pwrdm_wait_transition(pwrdm);
+                       sleep_switch = FORCEWAKEUP_SWITCH;
+               }
        }

        ret = pwrdm_set_next_pwrst(pwrdm, state);
@@ -126,12 +135,19 @@
                goto err;
        }

-       if (sleep_switch) {
+       switch (sleep_switch) {
+       case FORCEWAKEUP_SWITCH:
                omap2_clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]);
-               pwrdm_wait_transition(pwrdm);
-               pwrdm_state_switch(pwrdm);
+               break;
+       case LOWPOWERSTATE_SWITCH:
+               pwrdm_set_lowpwrstchange(pwrdm);
+               break;
+       default:
+               return ret;
        }

+       pwrdm_wait_transition(pwrdm);
+       pwrdm_state_switch(pwrdm);
 err:
        return ret;
 }


>
> Kevin
>
> > +           }
> >             omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
> >             sleep_switch = 1;
> >             pwrdm_wait_transition(pwrdm);
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