From ad98d75f2bf82f8cfef1e628e329c722be6c5ad1 Mon Sep 17 00:00:00 2001
From: Paul Mundt <lethal@linux-sh.org>
Date: Fri, 16 Oct 2009 17:20:58 +0900
Subject: [PATCH] --- yaml --- r: 173411 b: refs/heads/master c:
 f533c3d340536198a4889a42a68d6c0d79a504e7 h: refs/heads/master i:   173409:
 10b88224759dc3a8307b85196cab0d48b49be87a   173407:
 b038091660546f6e1cd338555411b282e6f104db v: v3

---
 [refs]                           |  2 +-
 trunk/arch/sh/include/asm/bugs.h |  4 ++
 trunk/arch/sh/kernel/idle.c      | 73 +++++++++++++++++++++++++-------
 3 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/[refs] b/[refs]
index d39799e5c57b..065a269e3676 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 94eab0bb206443dd7480349804f64e2bba8dc6e1
+refs/heads/master: f533c3d340536198a4889a42a68d6c0d79a504e7
diff --git a/trunk/arch/sh/include/asm/bugs.h b/trunk/arch/sh/include/asm/bugs.h
index 46260fcbdf4b..02a19a1c033a 100644
--- a/trunk/arch/sh/include/asm/bugs.h
+++ b/trunk/arch/sh/include/asm/bugs.h
@@ -14,11 +14,15 @@
 
 #include <asm/processor.h>
 
+extern void select_idle_routine(void);
+
 static void __init check_bugs(void)
 {
 	extern unsigned long loops_per_jiffy;
 	char *p = &init_utsname()->machine[2]; /* "sh" */
 
+	select_idle_routine();
+
 	current_cpu_data.loops_per_jiffy = loops_per_jiffy;
 
 	switch (current_cpu_data.family) {
diff --git a/trunk/arch/sh/kernel/idle.c b/trunk/arch/sh/kernel/idle.c
index 27ff2dc093c7..8e61241230cb 100644
--- a/trunk/arch/sh/kernel/idle.c
+++ b/trunk/arch/sh/kernel/idle.c
@@ -21,7 +21,7 @@
 #include <asm/atomic.h>
 
 static int hlt_counter;
-void (*pm_idle)(void);
+void (*pm_idle)(void) = NULL;
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
@@ -39,41 +39,68 @@ static int __init hlt_setup(char *__unused)
 }
 __setup("hlt", hlt_setup);
 
+static inline int hlt_works(void)
+{
+	return !hlt_counter;
+}
+
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->work.need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle(void)
+{
+	local_irq_enable();
+	while (!need_resched())
+		cpu_relax();
+}
+
 void default_idle(void)
 {
-	if (!hlt_counter) {
+	if (hlt_works()) {
 		clear_thread_flag(TIF_POLLING_NRFLAG);
 		smp_mb__after_clear_bit();
-		set_bl_bit();
-		stop_critical_timings();
 
-		while (!need_resched())
+		if (!need_resched()) {
+			local_irq_enable();
 			cpu_sleep();
+		}
 
-		start_critical_timings();
-		clear_bl_bit();
 		set_thread_flag(TIF_POLLING_NRFLAG);
 	} else
-		while (!need_resched())
-			cpu_relax();
+		poll_idle();
 }
 
+/*
+ * The idle thread. There's no useful work to be done, so just try to conserve
+ * power and have a low exit latency (ie sit in a loop waiting for somebody to
+ * say that they'd like to reschedule)
+ */
 void cpu_idle(void)
 {
+	unsigned int cpu = smp_processor_id();
+
 	set_thread_flag(TIF_POLLING_NRFLAG);
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		void (*idle)(void) = pm_idle;
+		tick_nohz_stop_sched_tick(1);
 
-		if (!idle)
-			idle = default_idle;
+		while (!need_resched() && cpu_online(cpu)) {
+			local_irq_disable();
+			/* Don't trace irqs off for idle */
+			stop_critical_timings();
+			pm_idle();
+			/*
+			 * Sanity check to ensure that pm_idle() returns
+			 * with IRQs enabled
+			 */
+			WARN_ON(irqs_disabled());
+			start_critical_timings();
+		}
 
-		tick_nohz_stop_sched_tick(1);
-		while (!need_resched())
-			idle();
 		tick_nohz_restart_sched_tick();
-
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
@@ -81,6 +108,20 @@ void cpu_idle(void)
 	}
 }
 
+void __cpuinit select_idle_routine(void)
+{
+	/*
+	 * If a platform has set its own idle routine, leave it alone.
+	 */
+	if (pm_idle)
+		return;
+
+	if (hlt_works())
+		pm_idle = default_idle;
+	else
+		pm_idle = poll_idle;
+}
+
 static void do_nothing(void *unused)
 {
 }