[PATCH 5.18 093/879] cpuidle: PSCI: Improve support for suspend-to-RAM for PSCI OSI mode

Greg Kroah-Hartman
2022-06-07T22:06:52Z

From: Ulf Hansson <ulf.hansson@linaro.org>

[ Upstream commit 171b66e2e2e9d80b93c8cff799e6175074b22297 ]

When PSCI OSI mode is supported the syscore flag is set for the CPU devices
that becomes attached to their PM domains (genpds). In the suspend-to-idle
case, we call dev_pm_genpd_suspend|resume() to allow genpd to properly
manage the power-off/on operations (pick an idlestate and manage the on/off
notifications).

For suspend-to-ram, dev_pm_genpd_suspend|resume() is currently not being
called, which causes a problem that the genpd on/off notifiers do not get
sent as expected. This prevents the platform-specific operations from being
executed, typically needed just before/after the boot CPU is being turned
off/on.

To deal with this problem, let's register a syscore ops for cpuidle-psci
when PSCI OSI mode is being used and call dev_pm_genpd_suspend|resume()
from them. In this way, genpd regains control of the PM domain topology and
then sends the on/off notifications when it's appropriate.

Reported-by: Maulik Shah <quic_mkshah@quicinc.com>
Suggested-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cpuidle/cpuidle-psci.c | 46 ++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index b51b5df08450..540105ca0781 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -23,6 +23,7 @@
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/syscore_ops.h>

#include <asm/cpuidle.h>

@@ -131,6 +132,49 @@ static int psci_idle_cpuhp_down(unsigned int cpu)
return 0;
}

+static void psci_idle_syscore_switch(bool suspend)
+{
+ bool cleared = false;
+ struct device *dev;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;
+
+ if (dev && suspend) {
+ dev_pm_genpd_suspend(dev);
+ } else if (dev) {
+ dev_pm_genpd_resume(dev);
+
+ /* Account for userspace having offlined a CPU. */
+ if (pm_runtime_status_suspended(dev))
+ pm_runtime_set_active(dev);
+
+ /* Clear domain state to re-start fresh. */
+ if (!cleared) {
+ psci_set_domain_state(0);
+ cleared = true;
+ }
+ }
+ }
+}
+
+static int psci_idle_syscore_suspend(void)
+{
+ psci_idle_syscore_switch(true);
+ return 0;
+}
+
+static void psci_idle_syscore_resume(void)
+{
+ psci_idle_syscore_switch(false);
+}
+
+static struct syscore_ops psci_idle_syscore_ops = {
+ .suspend = psci_idle_syscore_suspend,
+ .resume = psci_idle_syscore_resume,
+};
+
static void psci_idle_init_cpuhp(void)
{
int err;
@@ -138,6 +182,8 @@ 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,
--
2.35.1