Commit d7bdb8e6 authored by Ulf Hansson's avatar Ulf Hansson
Browse files

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: default avatarUlf Hansson <ulf.hansson@linaro.org>
Tested-by: Raghavendra Kakarla <quic_rkakarla@quicinc.com>  # qcm6490 with PREEMPT_RT set
Acked-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240527142557.321610-2-ulf.hansson@linaro.org
parent 328fc9b2

drivers/pmdomain/core.c

+46 −1
Original line number Diff line number Diff line
@@ -117,6 +117,48 @@ static const struct genpd_lock_ops genpd_spin_ops = { 
	.unlock = genpd_unlock_spin,

};



static void genpd_lock_raw_spin(struct generic_pm_domain *genpd)

	__acquires(&genpd->raw_slock)

{

	unsigned long flags;



	raw_spin_lock_irqsave(&genpd->raw_slock, flags);

	genpd->raw_lock_flags = flags;

}



static void genpd_lock_nested_raw_spin(struct generic_pm_domain *genpd,

					int depth)

	__acquires(&genpd->raw_slock)

{

	unsigned long flags;



	raw_spin_lock_irqsave_nested(&genpd->raw_slock, flags, depth);

	genpd->raw_lock_flags = flags;

}



static int genpd_lock_interruptible_raw_spin(struct generic_pm_domain *genpd)

	__acquires(&genpd->raw_slock)

{

	unsigned long flags;



	raw_spin_lock_irqsave(&genpd->raw_slock, flags);

	genpd->raw_lock_flags = flags;

	return 0;

}



static void genpd_unlock_raw_spin(struct generic_pm_domain *genpd)

	__releases(&genpd->raw_slock)

{

	raw_spin_unlock_irqrestore(&genpd->raw_slock, genpd->raw_lock_flags);

}



static const struct genpd_lock_ops genpd_raw_spin_ops = {

	.lock = genpd_lock_raw_spin,

	.lock_nested = genpd_lock_nested_raw_spin,

	.lock_interruptible = genpd_lock_interruptible_raw_spin,

	.unlock = genpd_unlock_raw_spin,

};



#define genpd_lock(p)			p->lock_ops->lock(p)

#define genpd_lock_nested(p, d)		p->lock_ops->lock_nested(p, d)

#define genpd_lock_interruptible(p)	p->lock_ops->lock_interruptible(p)
@@ -2143,7 +2185,10 @@ static void genpd_free_data(struct generic_pm_domain *genpd) 


static void genpd_lock_init(struct generic_pm_domain *genpd)

{

	if (genpd_is_irq_safe(genpd)) {

	if (genpd_is_cpu_domain(genpd)) {

		raw_spin_lock_init(&genpd->raw_slock);

		genpd->lock_ops = &genpd_raw_spin_ops;

	} else if (genpd_is_irq_safe(genpd)) {

		spin_lock_init(&genpd->slock);

		genpd->lock_ops = &genpd_spin_ops;

	} else {

include/linux/pm_domain.h

+4 −1
Original line number Diff line number Diff line
@@ -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)