Hi Nicolas,
On 01/27/2014 11:38 AM, Nicolas Pitre wrote:
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
arch/powerpc/platforms/pseries/processor_idle.c | 5 ++++ arch/powerpc/platforms/pseries/setup.c | 34 ++++++++++--------------- 2 files changed, 19 insertions(+), 20 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c index a166e38bd6..72ddfe3d2f 100644 --- a/arch/powerpc/platforms/pseries/processor_idle.c +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -33,6 +33,7 @@ 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
@@ -49,6 +50,10 @@ 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, diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index c1f1908587..7604c19d54 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;
}
/*
Reviewed-by: Preeti U Murthy preeti@linux.vnet.ibm.com
The consequence of this would be for other Power platforms like PowerNV, we will need to invoke ppc_runlatch_off() and ppc_runlatch_on() in each of the idle routines since the idle_loop_prologue() and idle_loop_epilogue() are not invoked by them, but we will take care of this.
Regards Preeti U Murthy