powerpc/pseries/cpuidle: smt-snooze-delay cleanup.

smt-snooze-delay was designed to disable NAP state or delay the entry
to the NAP state prior to adoption of cpuidle framework. This
is per-cpu variable. With the coming of CPUIDLE framework,
states can be disabled on per-cpu basis using the cpuidle/enable
sysfs entry.

Also, with the coming of cpuidle driver each state's target residency
is per-driver unlike earlier which was per-device. Therefore,
the per-cpu sysfs smt-snooze-delay which decides the target residency
of the idle state on a particular cpu causes more confusion to the user
as we cannot have different smt-snooze-delay (target residency)
values for each cpu.

In the current code, smt-snooze-delay functionality is completely broken.
It makes sense to remove smt-snooze-delay from idle driver with the
coming of cpuidle framework.
However, sysfs files are retained as ppc64_util currently
utilises it. Once we fix ppc64_util, propose to clean
up the kernel code.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/processor.h

@@ -450,13 +450,6 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 
 extern int powersave_nap;	/* set if nap mode can be used in idle loop */
 extern void power7_nap(void);
-
-#ifdef CONFIG_PSERIES_CPUIDLE
-extern void update_smt_snooze_delay(int cpu, int residency);
-#else
-static inline void update_smt_snooze_delay(int cpu, int residency) {}
-#endif
-
 extern void flush_instruction_cache(void);
 extern void hard_reset_now(void);
 extern void poweroff_now(void);

arch/powerpc/kernel/sysfs.c

@@ -51,8 +51,6 @@ static ssize_t store_smt_snooze_delay(struct device *dev,
 		return -EINVAL;
 
 	per_cpu(smt_snooze_delay, cpu->dev.id) = snooze;
-	update_smt_snooze_delay(cpu->dev.id, snooze);
-
 	return count;
 }
 

drivers/cpuidle/cpuidle-pseries.c

@@ -162,23 +162,6 @@ static struct cpuidle_state shared_states[] = {
 		.enter = &shared_cede_loop },
 };
 
-void update_smt_snooze_delay(int cpu, int residency)
-{
-	struct cpuidle_driver *drv = cpuidle_get_driver();
-	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
-
-	if (cpuidle_state_table != dedicated_states)
-		return;
-
-	if (residency < 0) {
-		/* Disable the Nap state on that cpu */
-		if (dev)
-			dev->states_usage[1].disable = 1;
-	} else
-		if (drv)
-			drv->states[1].target_residency = residency;
-}
-
 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
 			unsigned long action, void *hcpu)
 {