ARM: clean up idle handlers

Let's factor out the need_resched() check instead of having it duplicated
in every pm_idle implementations to avoid inconsistencies (omap2_pm_idle
is missing it already).

The forceful re-enablement of IRQs after pm_idle has returned can go.
The warning certainly doesn't trigger for existing users.

To get rid of the pm_idle calling convention oddity, let's introduce
arm_pm_idle() allowing for the local_irq_enable() to be factored out
from SOC specific implementations. The default pm_idle function becomes
a wrapper for arm_pm_idle and it takes care of enabling IRQs closer to
where they are initially disabled.

And finally move the comment explaining the reason for that turning off
of IRQs to a more proper location.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-and-tested-by: Jamie Iles <jamie@jamieiles.com>

2 files changed, 16 insertions, 8 deletions

diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index e4c96cc6ec0c..424aa458c487 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -110,6 +110,7 @@ extern void cpu_init(void);
 
 void soft_restart(unsigned long);
 extern void (*arm_pm_restart)(char str, const char *cmd);
+extern void (*arm_pm_idle)(void);
 
 #define UDBG_UNDEFINED  (1 << 0)
 #define UDBG_SYSCALL    (1 << 1)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 971d65c253a9..ba9e7ef92bec 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -181,12 +181,16 @@ void cpu_idle_wait(void)
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
 /*
- * This is our default idle handler.  We need to disable
- * interrupts here to ensure we don't miss a wakeup call.
+ * This is our default idle handler.
  */
+
+void (*arm_pm_idle)(void);
+
 static void default_idle(void)
 {
-        if (!need_resched())
+        if (arm_pm_idle)
+                arm_pm_idle();
+        else
                 arch_idle();
         local_irq_enable();
 }
@@ -215,6 +219,10 @@ void cpu_idle(void)
                                 cpu_die();
 #endif
 
+                        /*
+                         * We need to disable interrupts here
+                         * to ensure we don't miss a wakeup call.
+                         */
                         local_irq_disable();
 #ifdef CONFIG_PL310_ERRATA_769419
                         wmb();
@@ -222,19 +230,18 @@ void cpu_idle(void)
                         if (hlt_counter) {
                                 local_irq_enable();
                                 cpu_relax();
-                        } else {
+                        } else if (!need_resched()) {
                                 stop_critical_timings();
                                 if (cpuidle_idle_call())
                                         pm_idle();
                                 start_critical_timings();
                                 /*
-                                 * This will eventually be removed - pm_idle
-                                 * functions should always return with IRQs
-                                 * enabled.
+                                 * pm_idle functions must always
+                                 * return with IRQs enabled.
                                  */
                                 WARN_ON(irqs_disabled());
+                        } else
                                 local_irq_enable();
-                        }
                 }
                 leds_event(led_idle_end);
                 rcu_idle_exit();