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Subject[RFC 6/7] arm: cpuidle: let genpd handle the cluster power transition with 'power-states'
Date
From: Marc Titinger <mtitinger@baylibre.com>

Cpuidle now handles c-states and power-states differently. c-states do not decrement
the reference count for the CPUs in the cluster, while power-states i.e.
cluster level states like 'CLUSTER_SLEEP_0' in the case of juno, will.

The 'D1' fake device also registers intermediate power-state,
for experimentation.

Signed-off-by: Marc Titinger <mtitinger@baylibre.com>
---
arch/arm64/boot/dts/arm/juno.dts | 2 +-
drivers/cpuidle/cpuidle-arm.c | 50 ++++++++++++++++++++++++++++++++--------
2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/boot/dts/arm/juno.dts b/arch/arm64/boot/dts/arm/juno.dts
index cadc5de..0bb0dd7 100644
--- a/arch/arm64/boot/dts/arm/juno.dts
+++ b/arch/arm64/boot/dts/arm/juno.dts
@@ -47,7 +47,7 @@
};

CLUSTER_SLEEP_0: cluster-sleep-0 {
- compatible = "arm,idle-state","arm,power-state";
+ compatible = "arm,power-state";
arm,psci-suspend-param = <0x1010000>;
local-timer-stop;
entry-latency-us = <800>;
diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index ca118ed..592bb1cb 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -39,7 +39,6 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int idx)
{
int ret;
- struct device *cpu_dev = get_cpu_device(dev->cpu);

if (!idx) {
cpu_do_idle();
@@ -48,11 +47,6 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,

ret = cpu_pm_enter();
if (!ret) {
- /*
- * Notify runtime PM as well of this cpu powering down
- * TODO: Merge CPU_PM and runtime PM.
- */
- pm_runtime_put_sync(cpu_dev);

/*
* Pass idle state index to cpu_suspend which in turn will
@@ -61,6 +55,43 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
*/
arm_cpuidle_suspend(idx);

+ cpu_pm_exit();
+ }
+
+ return ret ? -1 : idx;
+}
+
+/*
+ * arm_enter_power_state - delegate state trasition to genpd
+ *
+ * dev: cpuidle device
+ * drv: cpuidle driver
+ * idx: state index
+ *
+ * Called from the CPUidle framework to delegate a state transition
+ * to the generic domain. This will be a cluster poweroff state
+ * the Domain will chose to actually turn off the cluster based on
+ * the status of other CPUs, and devices and subdomains in the Cluster
+ * domain.
+ */
+static int arm_enter_power_state(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int idx)
+{
+ int ret;
+ struct device *cpu_dev = get_cpu_device(dev->cpu);
+
+ BUG_ON(idx == 0);
+
+ ret = cpu_pm_enter();
+ if (!ret) {
+ /*
+ * Notify runtime PM as well of this cpu powering down
+ * TODO: Merge CPU_PM and runtime PM.
+ */
+ pm_runtime_put_sync(cpu_dev);
+
+ arm_cpuidle_suspend(idx);
+
pm_runtime_get_sync(cpu_dev);
cpu_pm_exit();
}
@@ -89,9 +120,10 @@ static struct cpuidle_driver arm_idle_driver = {
};

static const struct of_device_id arm_idle_state_match[] __initconst = {
- { .compatible = "arm,idle-state",
- .data = arm_enter_idle_state },
- { },
+ {.compatible = "arm,idle-state",
+ .data = arm_enter_idle_state},
+ {.compatible = "arm,power-state",
+ .data = arm_enter_power_state},
};

/*
--
1.9.1


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