[tip:sched/core] sched/idle, PPC: Remove redundant cpuidle_idle_call()

[tip-bot for Nicolas Pitre]

Commit-ID:  d8c6ad3184ca6516a5cf457af1afaa293d8f09c0
Gitweb:     http://git.kernel.org/tip/d8c6ad3184ca6516a5cf457af1afaa293d8f09c0
Author:     Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
AuthorDate: Wed, 29 Jan 2014 12:45:10 -0500
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 11 Feb 2014 09:58:24 +0100

sched/idle, PPC: Remove redundant cpuidle_idle_call()

The core idle loop now takes care of it.  However a few things need
checking:

- Invocation of cpuidle_idle_call() in pseries_lpar_idle() happened
  through arch_cpu_idle() and was therefore always preceded by a call
  to ppc64_runlatch_off().  To preserve this property now that
  cpuidle_idle_call() is invoked directly from core code, a call to
  ppc64_runlatch_off() has been added to idle_loop_prolog() in
  platforms/pseries/processor_idle.c.

- Similarly, cpuidle_idle_call() was followed by ppc64_runlatch_off()
  so a call to the later has been added to idle_loop_epilog().

- And since arch_cpu_idle() always made sure to re-enable IRQs if they
  were not enabled, this is now
  done in idle_loop_epilog() as well.

The above was made in order to keep the execution flow close to the
original.  I don't know if that was strictly necessary. Someone well
aquainted with the platform details might find some room for possible
optimizations.

Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
Reviewed-by: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: linux-sh@xxxxxxxxxxxxxxx
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: linaro-kernel@xxxxxxxxxxxxxxxx
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-47o4m03citrfg9y1vxic5asb@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/powerpc/platforms/pseries/setup.c | 34 ++++++++++++++--------------------
 drivers/cpuidle/cpuidle-pseries.c      |  5 +++++
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 8e639d7..c737d55 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -39,7 +39,6 @@
 #include <linux/irq.h>
 #include <linux/seq_file.h>
 #include <linux/root_dev.h>
-#include <linux/cpuidle.h>
 #include <linux/of.h>
 #include <linux/kexec.h>
 
@@ -356,29 +355,24 @@ early_initcall(alloc_dispatch_log_kmem_cache);
 
 static void pseries_lpar_idle(void)
 {
-	/* This would call on the cpuidle framework, and the back-end pseries
-	 * driver to  go to idle states
+	/*
+	 * Default handler to go into low thread priority and possibly
+	 * low power mode by cedeing processor to hypervisor
 	 */
-	if (cpuidle_idle_call()) {
-		/* On error, execute default handler
-		 * to go into low thread priority and possibly
-		 * low power mode by cedeing processor to hypervisor
-		 */
 
-		/* Indicate to hypervisor that we are idle. */
-		get_lppaca()->idle = 1;
+	/* Indicate to hypervisor that we are idle. */
+	get_lppaca()->idle = 1;
 
-		/*
-		 * Yield the processor to the hypervisor.  We return if
-		 * an external interrupt occurs (which are driven prior
-		 * to returning here) or if a prod occurs from another
-		 * processor. When returning here, external interrupts
-		 * are enabled.
-		 */
-		cede_processor();
+	/*
+	 * Yield the processor to the hypervisor.  We return if
+	 * an external interrupt occurs (which are driven prior
+	 * to returning here) or if a prod occurs from another
+	 * processor. When returning here, external interrupts
+	 * are enabled.
+	 */
+	cede_processor();
 
-		get_lppaca()->idle = 0;
-	}
+	get_lppaca()->idle = 0;
 }
 
 /*
diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c
index 7ab564a..d486489 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -29,6 +29,7 @@ static struct cpuidle_state *cpuidle_state_table;
 
 static inline void idle_loop_prolog(unsigned long *in_purr)
 {
+	ppc64_runlatch_off();
 	*in_purr = mfspr(SPRN_PURR);
 	/*
 	 * Indicate to the HV that we are idle. Now would be
@@ -45,6 +46,10 @@ static inline void idle_loop_epilog(unsigned long in_purr)
 	wait_cycles += mfspr(SPRN_PURR) - in_purr;
 	get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
 	get_lppaca()->idle = 0;
+
+	if (irqs_disabled())
+		local_irq_enable();
+	ppc64_runlatch_on();
 }
 
 static int snooze_loop(struct cpuidle_device *dev,
--
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