cpuidle: psci-domain: Enable system-wide suspend on PREEMPT_RT

The domain-idle-states are currently disabled on a PREEMPT_RT based
configuration for the cpuidle-psci-domain. To enable them to be used for
system-wide suspend and in particular during s2idle, let's set the
GENPD_FLAG_RPM_ALWAYS_ON instead of GENPD_FLAG_ALWAYS_ON for the
corresponding genpd provider.

In this way, the runtime PM path remains disabled in genpd for its attached
devices, while powering-on/off the PM domain during system-wide suspend
becomes allowed.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Raghavendra Kakarla <quic_rkakarla@quicinc.com>  # qcm6490 with PREEMPT_RT set
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240527142557.321610-5-ulf.hansson@linaro.org

diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index fae9587943397b98888b2c05d8d6b3e1cf4cc403..ea28b73ef3fb6c535dbf79739144f76431d48eef 100644 (file)
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -67,12 +67,16 @@ static int psci_pd_init(struct device_node *np, bool use_osi)
 
        /*
         * Allow power off when OSI has been successfully enabled.
-        * PREEMPT_RT is not yet ready to enter domain idle states.
+        * On a PREEMPT_RT based configuration the domain idle states are
+        * supported, but only during system-wide suspend.
         */
-       if (use_osi && !IS_ENABLED(CONFIG_PREEMPT_RT))
+       if (use_osi) {
                pd->power_off = psci_pd_power_off;
-       else
+               if (IS_ENABLED(CONFIG_PREEMPT_RT))
+                       pd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
+       } else {
                pd->flags |= GENPD_FLAG_ALWAYS_ON;
+       }
 
        /* Use governor for CPU PM domains if it has some states to manage. */
        pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;