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@linaro.org>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linaro-kernel@lists.linaro.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-47o4m03citrfg9y1vxic5asb@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 8e639d7cbda72e057ab535083e29ef03f8d7f369..c737d554571a4088e138f90ba394f7a16c32a624 100644 (file)
--- 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 7ab564aa0b1c8c141e0b64f750592dc44bbbba3f..d4864892951b618cd3e2a42e2128078c97f8909c 100644 (file)
--- 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,