[RFC/PATCH 2/2] OMAP3: CPUidle: trigger early idle notification call chain

[Kevin Hilman]

During the early part of the CPUidle path (state selection by the
governer, checking for device activity, etc.) there is no (good)
reason to have interrupts disabled.

Therefore, enable interrupts early in the CPUidle path and then
trigger the "early" idle notifier call chain after device activity
checks and the next power states have been programmed.  Interrupts are
then (re)disabled after the final state is selected.

Signed-off-by: Kevin Hilman <khilman at deeprootsystems.com>
---
 arch/arm/mach-omap2/cpuidle34xx.c |   27 ++++++++++++++++++++++++---
 1 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 0d50b45..8c57360 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -30,6 +30,7 @@
 #include <plat/powerdomain.h>
 #include <plat/clockdomain.h>
 #include <plat/serial.h>
+#include <plat/common.h>
 
 #include "pm.h"
 #include "control.h"
@@ -128,12 +129,14 @@ static int omap3_enter_idle(struct cpuidle_device *dev,
 	/* Used to keep track of the total time in idle */
 	getnstimeofday(&ts_preidle);
 
-	local_irq_disable();
-	local_fiq_disable();
-
 	pwrdm_set_next_pwrst(mpu_pd, mpu_state);
 	pwrdm_set_next_pwrst(core_pd, core_state);
 
+	omap_early_idle_notifier_start();
+
+	local_irq_disable();
+	local_fiq_disable();
+
 	if (omap_irq_pending() || need_resched())
 		goto return_sleep_time;
 
@@ -157,6 +160,8 @@ return_sleep_time:
 	local_irq_enable();
 	local_fiq_enable();
 
+	omap_early_idle_notifier_end();
+
 	return ts_idle.tv_nsec / NSEC_PER_USEC + ts_idle.tv_sec * USEC_PER_SEC;
 }
 
@@ -459,6 +464,21 @@ struct cpuidle_driver omap3_idle_driver = {
 	.owner = 	THIS_MODULE,
 };
 
+static int omap3_idle_prepare(struct cpuidle_device *dev)
+{
+	/*
+	 * Enable interrupts during the early part of the CPUidle path.
+	 * They are later (re)disabled when the final state is selected.
+	 *
+	 * The primary reason for this is to enable non-atomic idle
+	 * notifications to drivers that want to coordinate device
+	 * idle transitions with CPU idle transitions.
+	 */
+	local_irq_enable();
+
+	return 0;
+}
+
 /**
  * omap3_idle_init - Init routine for OMAP3 idle
  *
@@ -482,6 +502,7 @@ int __init omap3_idle_init(void)
 
 	dev = &per_cpu(omap3_idle_dev, smp_processor_id());
 
+	dev->prepare = omap3_idle_prepare;
 	for (i = OMAP3_STATE_C1; i < OMAP3_MAX_STATES; i++) {
 		cx = &omap3_power_states[i];
 		state = &dev->states[count];
-- 
1.7.2.1