pmdomain: core: Enable s2idle for CPU PM domains on PREEMPT_RT

To allow a genpd provider for a CPU PM domain to enter a domain-idle-state
during s2idle on a PREEMPT_RT based configuration, we can't use the regular
spinlock, as they are turned into sleepable locks on PREEMPT_RT.

To address this problem, let's convert into using the raw spinlock, but
only for genpd providers that have the GENPD_FLAG_CPU_DOMAIN bit set. In
this way, the lock can still be acquired/released in atomic context, which
is needed in the idle-path for PREEMPT_RT.

Do note that the genpd power-on/off notifiers may also be fired during
s2idle, but these are already prepared for PREEMPT_RT as they are based on
the raw notifiers. However, consumers of them may need to adopt accordingly
to work properly on PREEMPT_RT.

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/20240527142557.321610-2-ulf.hansson@linaro.org

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 858c8e7851fb..b86bb52858ac 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -198,8 +198,11 @@ struct generic_pm_domain {
 			spinlock_t slock;
 			unsigned long lock_flags;
 		};
+		struct {
+			raw_spinlock_t raw_slock;
+			unsigned long raw_lock_flags;
+		};
 	};
-
 };
 
 static inline struct generic_pm_domain *pd_to_genpd(struct dev_pm_domain *pd)