Hi Daniel,

On 07/27/2013 10:57 AM, Daniel Lezcano wrote:

On 07/23/2013 11:01 AM, Deepthi Dharwar wrote:

quoted

This patch implements a back-end cpuidle driver for
powernv calling power7_nap and snooze idle states.
This can be extended by adding more idle states
in the future to the existing framework.

Signed-off-by: Deepthi Dharwar <redacted>
---
 arch/powerpc/platforms/powernv/Kconfig          |    9 +
 arch/powerpc/platforms/powernv/Makefile         |    1 
 arch/powerpc/platforms/powernv/processor_idle.c |  239 +++++++++++++++++++++++
 3 files changed, 249 insertions(+)
 create mode 100644 arch/powerpc/platforms/powernv/processor_idle.c

diff --git a/arch/powerpc/platforms/powernv/processor_idle.c b/arch/powerpc/platforms/powernv/processor_idle.c
new file mode 100644
index 0000000..f43ad91a
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/processor_idle.c

@@ -0,0 +1,239 @@
+/*
+ *  processor_idle - idle state cpuidle driver.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/cpuidle.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+
+#include <asm/machdep.h>
+#include <asm/runlatch.h>
+
+struct cpuidle_driver powernv_idle_driver = {
+	.name =		"powernv_idle",
+	.owner =	THIS_MODULE,
+};
+
+#define MAX_IDLE_STATE_COUNT	2
+
+static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
+static struct cpuidle_device __percpu *powernv_cpuidle_devices;
+static struct cpuidle_state *cpuidle_state_table;
+
+static int snooze_loop(struct cpuidle_device *dev,
+			struct cpuidle_driver *drv,
+			int index)
+{
+	int cpu = dev->cpu;
+
+	local_irq_enable();
+	set_thread_flag(TIF_POLLING_NRFLAG);
+
+	while ((!need_resched()) && cpu_online(cpu)) {
+		ppc64_runlatch_off();
+		HMT_very_low();
+	}

Why are you using the cpu_online test here ?

quoted

+
+	HMT_medium();
+	clear_thread_flag(TIF_POLLING_NRFLAG);
+	smp_mb();
+	return index;
+}
+
+
+static int nap_loop(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index)
+{
+	ppc64_runlatch_off();
+	power7_idle();
+	return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state powernv_states[MAX_IDLE_STATE_COUNT] = {
+	{ /* Snooze */
+		.name = "snooze",
+		.desc = "snooze",
+		.flags = CPUIDLE_FLAG_TIME_VALID,
+		.exit_latency = 0,
+		.target_residency = 0,
+		.enter = &snooze_loop },
+	 { /* Nap */
+		.name = "Nap",
+		.desc = "Nap",
+		.flags = CPUIDLE_FLAG_TIME_VALID,
+		.exit_latency = 10,
+		.target_residency = 100,
+		.enter = &nap_loop },
+};
+
+static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
+			unsigned long action, void *hcpu)
+{
+	int hotcpu = (unsigned long)hcpu;
+	struct cpuidle_device *dev =
+			per_cpu_ptr(powernv_cpuidle_devices, hotcpu);
+
+	if (dev && cpuidle_get_driver()) {
+		switch (action) {
+		case CPU_ONLINE:
+		case CPU_ONLINE_FROZEN:
+			cpuidle_pause_and_lock();
+			cpuidle_enable_device(dev);
+			cpuidle_resume_and_unlock();
+			break;
+
+		case CPU_DEAD:
+		case CPU_DEAD_FROZEN:
+			cpuidle_pause_and_lock();
+			cpuidle_disable_device(dev);
+			cpuidle_resume_and_unlock();
+			break;
+
+		default:
+			return NOTIFY_DONE;
+		}
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block setup_hotplug_notifier = {
+	.notifier_call = powernv_cpuidle_add_cpu_notifier,
+};

This is duplicated code with the pseries cpuidle driver and IMHO it
should be moved to the cpuidle framework.

Will this not require a cleanup of the hotplug cpuidle notifiers from
other architectures into the cpuidle framework as well?

Regards
Preeti U Murthy