[PATCH v2 6/7] cpuidle: psci: Enable the hierarchical topology for s2ram on PREEMPT_RT

Ulf Hansson
2024-05-27T14:26:17Z

The hierarchical PM domain topology are currently disabled on a PREEMPT_RT
based configuration. As a first step to enable it to be used, let's try to
attach the CPU devices to their PM domains on PREEMPT_RT. In this way the
syscore ops becomes available, allowing the PM domain topology to be
managed during s2ram.

For the moment let's leave the support for CPU hotplug outside PREEMPT_RT,
as it's depending on using runtime PM. For s2ram, this isn't a problem as
all CPUs are managed via the syscore ops.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
Changes in v2:
- None.
---
drivers/cpuidle/cpuidle-psci.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index d82a8bc1b194..ad6ce9fe12b4 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -37,6 +37,7 @@ struct psci_cpuidle_data {

static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
static DEFINE_PER_CPU(u32, domain_state);
+static bool psci_cpuidle_use_syscore;
static bool psci_cpuidle_use_cpuhp;

void psci_set_domain_state(u32 state)
@@ -166,6 +167,12 @@ static struct syscore_ops psci_idle_syscore_ops = {
.resume = psci_idle_syscore_resume,
};

+static void psci_idle_init_syscore(void)
+{
+ if (psci_cpuidle_use_syscore)
+ register_syscore_ops(&psci_idle_syscore_ops);
+}
+
static void psci_idle_init_cpuhp(void)
{
int err;
@@ -173,8 +180,6 @@ static void psci_idle_init_cpuhp(void)
if (!psci_cpuidle_use_cpuhp)
return;

- register_syscore_ops(&psci_idle_syscore_ops);
-
err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
"cpuidle/psci:online",
psci_idle_cpuhp_up,
@@ -222,13 +227,16 @@ static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
if (!psci_has_osi_support())
return 0;

- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- return 0;
-
data->dev = dt_idle_attach_cpu(cpu, "psci");
if (IS_ERR_OR_NULL(data->dev))
return PTR_ERR_OR_ZERO(data->dev);

+ psci_cpuidle_use_syscore = true;
+
+ /* The hierarchical topology is limited to s2ram on PREEMPT_RT. */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT))
+ return 0;
+
/*
* Using the deepest state for the CPU to trigger a potential selection
* of a shared state for the domain, assumes the domain states are all
@@ -312,6 +320,7 @@ static void psci_cpu_deinit_idle(int cpu)
struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);

dt_idle_detach_cpu(data->dev);
+ psci_cpuidle_use_syscore = false;
psci_cpuidle_use_cpuhp = false;
}

@@ -408,6 +417,7 @@ static int psci_cpuidle_probe(struct platform_device *pdev)
goto out_fail;
}

+ psci_idle_init_syscore();
psci_idle_init_cpuhp();
return 0;

--
2.34.1