[PATCH v2 0/5] pmdomain/cpuidle-psci: Fix behaviours for CPU PM domains

[PATCH v2 0/5] pmdomain/cpuidle-psci: Fix behaviours for CPU PM domains

[Ulf Hansson]

From: Ulf Hansson <ulfh@kernel.org>

This series fixes a couple of different, but highly related problems, when
dealing with CPU PM domains. More details are available in the commit messages
for each patch.

Note that, this series is a follow up to fix problems that have been pointed
out in a series [1] from Yuanfang Zhang (Qcom), to add support for new
components for the arm coresight subsystem.

Changes in v2:
	- Dropped the RFC.
	- See updates in the changelog for each patch.

Kind regards
Uffe

[1]
[PATCH v2 00/12] coresight: Add CPU cluster funnel/replicator/tmc support
https://lore.kernel.org/all/20251218-cpu_cluster_component_pm-v2-0-2335a6ae62a0@oss.qualcomm.com/#r


Ulf Hansson (5):
  pmdomain: core: Rename genpd_status_on()
  pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power
    on
  pmdomain: core: Add a genpd config to support unknown initial status
  cpuidle: psci: Initialize the PM domains in powered off state for OSI
  cpuidle: psci: Move initialization a bit earlier in the boot sequence

 drivers/cpuidle/cpuidle-psci-domain.c |   5 +-
 drivers/cpuidle/cpuidle-psci.c        |   2 +-
 drivers/pmdomain/core.c               | 111 +++++++++++++++++++++-----
 include/linux/pm_domain.h             |   9 +++
 4 files changed, 106 insertions(+), 21 deletions(-)

-- 
2.43.0

[PATCH v2 1/5] pmdomain: core: Rename genpd_status_on()

[Ulf Hansson]

Let's rename the internal function genpd_status_on() to
genpd_status_on_unlocked() to clarify its use.

Suggested-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
---

Changes in v2:
	- New patch.

---
 drivers/pmdomain/core.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 842c4169e290..6ac1ce18fda3 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -173,7 +173,7 @@ static const struct genpd_lock_ops genpd_raw_spin_ops = {
 #define genpd_lock_interruptible(p)	p->lock_ops->lock_interruptible(p)
 #define genpd_unlock(p)			p->lock_ops->unlock(p)
 
-#define genpd_status_on(genpd)		(genpd->status == GENPD_STATE_ON)
+#define genpd_status_on_unlocked(genpd)	(genpd->status == GENPD_STATE_ON)
 #define genpd_is_irq_safe(genpd)	(genpd->flags & GENPD_FLAG_IRQ_SAFE)
 #define genpd_is_always_on(genpd)	(genpd->flags & GENPD_FLAG_ALWAYS_ON)
 #define genpd_is_active_wakeup(genpd)	(genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
@@ -771,7 +771,7 @@ EXPORT_SYMBOL_GPL(dev_pm_genpd_rpm_always_on);
  * @dev: Device to get the current power status
  *
  * This function checks whether the generic power domain associated with the
- * given device is on or not by verifying if genpd_status_on equals
+ * given device is on or not by verifying if genpd_status_on_unlocked equals
  * GENPD_STATE_ON.
  *
  * Note: this function returns the power status of the genpd at the time of the
@@ -791,7 +791,7 @@ bool dev_pm_genpd_is_on(struct device *dev)
 		return false;
 
 	genpd_lock(genpd);
-	is_on = genpd_status_on(genpd);
+	is_on = genpd_status_on_unlocked(genpd);
 	genpd_unlock(genpd);
 
 	return is_on;
@@ -963,7 +963,7 @@ static void genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
 	 * The domain was on at boot and still need to stay on.
 	 * The domain has a subdomain being powered on.
 	 */
-	if (!genpd_status_on(genpd) || genpd->prepared_count > 0 ||
+	if (!genpd_status_on_unlocked(genpd) || genpd->prepared_count > 0 ||
 	    genpd_is_always_on(genpd) || genpd_is_rpm_always_on(genpd) ||
 	    genpd->stay_on || atomic_read(&genpd->sd_count) > 0)
 		return;
@@ -1040,7 +1040,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
 	struct gpd_link *link;
 	int ret = 0;
 
-	if (genpd_status_on(genpd))
+	if (genpd_status_on_unlocked(genpd))
 		return 0;
 
 	/* Reflect over the entered idle-states residency for debugfs. */
@@ -1406,7 +1406,7 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
 {
 	struct gpd_link *link;
 
-	if (!genpd_status_on(genpd) || genpd_is_always_on(genpd))
+	if (!genpd_status_on_unlocked(genpd) || genpd_is_always_on(genpd))
 		return;
 
 	if (genpd->suspended_count != genpd->device_count
@@ -1472,7 +1472,7 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
 {
 	struct gpd_link *link;
 
-	if (genpd_status_on(genpd))
+	if (genpd_status_on_unlocked(genpd))
 		return;
 
 	list_for_each_entry(link, &genpd->child_links, child_node) {
@@ -2170,7 +2170,8 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,
 	genpd_lock(subdomain);
 	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
 
-	if (!genpd_status_on(genpd) && genpd_status_on(subdomain)) {
+	if (!genpd_status_on_unlocked(genpd) &&
+	    genpd_status_on_unlocked(subdomain)) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -2186,7 +2187,7 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,
 	list_add_tail(&link->parent_node, &genpd->parent_links);
 	link->child = subdomain;
 	list_add_tail(&link->child_node, &subdomain->child_links);
-	if (genpd_status_on(subdomain))
+	if (genpd_status_on_unlocked(subdomain))
 		genpd_sd_counter_inc(genpd);
 
  out:
@@ -2246,7 +2247,7 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 		list_del(&link->parent_node);
 		list_del(&link->child_node);
 		kfree(link);
-		if (genpd_status_on(subdomain))
+		if (genpd_status_on_unlocked(subdomain))
 			genpd_sd_counter_dec(genpd);
 
 		ret = 0;
@@ -2441,7 +2442,7 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 
 	/* Always-on domains must be powered on at initialization. */
 	if ((genpd_is_always_on(genpd) || genpd_is_rpm_always_on(genpd)) &&
-			!genpd_status_on(genpd)) {
+			!genpd_status_on_unlocked(genpd)) {
 		pr_err("always-on PM domain %s is not on\n", genpd->name);
 		return -EINVAL;
 	}
@@ -3839,7 +3840,7 @@ static int genpd_summary_one(struct seq_file *s,
 
 	if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup)))
 		goto exit;
-	if (!genpd_status_on(genpd))
+	if (!genpd_status_on_unlocked(genpd))
 		snprintf(state, sizeof(state), "%s-%u",
 			 status_lookup[genpd->status], genpd->state_idx);
 	else
-- 
2.43.0

Re: [PATCH v2 1/5] pmdomain: core: Rename genpd_status_on()

[Dhruva G]

Hi Ulf,

On 01-09-2026 16:44, Ulf Hansson wrote:
> Let's rename the internal function genpd_status_on() to
> genpd_status_on_unlocked() to clarify its use.
> 
> Suggested-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
> ---

Optional:
An additional line explaining why this otherwise unnecessary rename exists:

Rename the accessor to leave genpd_status_on() available for a lock-taking wrapper
introduced in a future commit.


> 
> Changes in v2:
> 	- New patch.
> 
> ---
>  drivers/pmdomain/core.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 842c4169e290..6ac1ce18fda3 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -173,7 +173,7 @@ static const struct genpd_lock_ops genpd_raw_spin_ops = {
>  #define genpd_lock_interruptible(p)	p->lock_ops->lock_interruptible(p)
>  #define genpd_unlock(p)			p->lock_ops->unlock(p)
>  
> -#define genpd_status_on(genpd)		(genpd->status == GENPD_STATE_ON)
> +#define genpd_status_on_unlocked(genpd)	(genpd->status == GENPD_STATE_ON)
>  #define genpd_is_irq_safe(genpd)	(genpd->flags & GENPD_FLAG_IRQ_SAFE)
>  #define genpd_is_always_on(genpd)	(genpd->flags & GENPD_FLAG_ALWAYS_ON)
>  #define genpd_is_active_wakeup(genpd)	(genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
> @@ -771,7 +771,7 @@ EXPORT_SYMBOL_GPL(dev_pm_genpd_rpm_always_on);
>   * @dev: Device to get the current power status
>   *
>   * This function checks whether the generic power domain associated with the
> - * given device is on or not by verifying if genpd_status_on equals
> + * given device is on or not by verifying if genpd_status_on_unlocked equals
>   * GENPD_STATE_ON.

Since we're fixing this anyway, It should describe comparing genpd->status with GENPD_STATE_ON, not the macro
which expands to that logic ;)

Anyway, nits only, LGTM otherwise.

Reviewed-by: Dhruva Gole <goledhruva@gmail.com>

Re: [PATCH v2 1/5] pmdomain: core: Rename genpd_status_on()

[Ulf Hansson]

On Thu, Sep 3, 2026 at 2:00 PM Dhruva G <goledhruva@gmail.com> wrote:
>
> Hi Ulf,
>
> On 01-09-2026 16:44, Ulf Hansson wrote:
> > Let's rename the internal function genpd_status_on() to
> > genpd_status_on_unlocked() to clarify its use.
> >
> > Suggested-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
> > Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
> > ---
>
> Optional:
> An additional line explaining why this otherwise unnecessary rename exists:
>
> Rename the accessor to leave genpd_status_on() available for a lock-taking wrapper
> introduced in a future commit.

Yeah, good point!

>
>
> >
> > Changes in v2:
> >       - New patch.
> >
> > ---
> >  drivers/pmdomain/core.c | 25 +++++++++++++------------
> >  1 file changed, 13 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> > index 842c4169e290..6ac1ce18fda3 100644
> > --- a/drivers/pmdomain/core.c
> > +++ b/drivers/pmdomain/core.c
> > @@ -173,7 +173,7 @@ static const struct genpd_lock_ops genpd_raw_spin_ops = {
> >  #define genpd_lock_interruptible(p)  p->lock_ops->lock_interruptible(p)
> >  #define genpd_unlock(p)                      p->lock_ops->unlock(p)
> >
> > -#define genpd_status_on(genpd)               (genpd->status == GENPD_STATE_ON)
> > +#define genpd_status_on_unlocked(genpd)      (genpd->status == GENPD_STATE_ON)
> >  #define genpd_is_irq_safe(genpd)     (genpd->flags & GENPD_FLAG_IRQ_SAFE)
> >  #define genpd_is_always_on(genpd)    (genpd->flags & GENPD_FLAG_ALWAYS_ON)
> >  #define genpd_is_active_wakeup(genpd)        (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
> > @@ -771,7 +771,7 @@ EXPORT_SYMBOL_GPL(dev_pm_genpd_rpm_always_on);
> >   * @dev: Device to get the current power status
> >   *
> >   * This function checks whether the generic power domain associated with the
> > - * given device is on or not by verifying if genpd_status_on equals
> > + * given device is on or not by verifying if genpd_status_on_unlocked equals
> >   * GENPD_STATE_ON.
>
> Since we're fixing this anyway, It should describe comparing genpd->status with GENPD_STATE_ON, not the macro
> which expands to that logic ;)

Of course, my search/replace logic was too lazy.

>
> Anyway, nits only, LGTM otherwise.
>
> Reviewed-by: Dhruva Gole <goledhruva@gmail.com>
>
>

Thanks, I will send a new version to address your comments!

Kind regards
Uffe

[PATCH v2 2/5] pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power on

[Ulf Hansson]

A driver for a non-CPU device that is attached to a CPU PM domain (the
genpd has the GENPD_FLAG_CPU_DOMAIN configuration set), is currently not
able to power on the PM domain. More precisely, to power on a CPU PM domain
one of its corresponding CPUs needs to be woken up if they are idle.

The current support for a non-CPU device is that its driver can only
prevent an already powered on CPU PM domain from being powered off. This
leads to problems for a driver while probing its device or when it needs to
call pm_runtime_get_sync() to turn on the power for it. From the driver
point of view it looks like it all works fine, but when accessing the
device it may end up with various errors as the device may not be fully
powered on.

To fix the behavior for these types of devices, let's adjust the behaviour
in genpd_power_on() to wake up an idle CPU that belongs to it, in cases
when it's needed.

Link: https://lore.kernel.org/all/CAPx+jO-sCierYj8jnoKQHckJG16dOBxnNrsZVYO=38R2cLV8nw@mail.gmail.com/
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
---

Changes in v2:
	- Rename a function according to Abel's suggestion.

---
 drivers/pmdomain/core.c | 80 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 75 insertions(+), 5 deletions(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 6ac1ce18fda3..97273ed2f825 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -10,6 +10,7 @@
 #include <linux/idr.h>
 #include <linux/kernel.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
@@ -19,11 +20,14 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/sched.h>
+#include <linux/smp.h>
 #include <linux/suspend.h>
 #include <linux/export.h>
 #include <linux/cpu.h>
 #include <linux/debugfs.h>
 
+#include <trace/events/ipi.h>
+
 /* Provides a unique ID for each genpd device */
 static DEFINE_IDA(genpd_ida);
 
@@ -32,7 +36,9 @@ static const struct bus_type genpd_provider_bus_type = {
 	.name		= "genpd_provider",
 };
 
-#define GENPD_RETRY_MAX_MS	250		/* Approximate */
+#define GENPD_RETRY_MAX_MS		250		/* Approximate */
+#define GENPD_CPU_ON_POLL_PERIOD_US	100		/* 100us */
+#define GENPD_CPU_ON_TIMEOUT_US		5000000		/* 5s */
 
 #define GENPD_DEV_CALLBACK(genpd, type, callback, dev)		\
 ({								\
@@ -1027,15 +1033,75 @@ static void genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
 	}
 }
 
+static bool genpd_status_on(struct generic_pm_domain *genpd)
+{
+	bool is_on;
+
+	genpd_lock(genpd);
+	is_on = genpd_status_on_unlocked(genpd);
+	genpd_unlock(genpd);
+
+	return is_on;
+}
+
+static int genpd_wakeup_cpu(struct generic_pm_domain *genpd)
+{
+	unsigned int cpu;
+	bool is_on;
+	int ret;
+
+	/* Find the first online CPU in the genpd's cpumask. */
+	cpu = cpumask_first_and(genpd->cpus, cpu_online_mask);
+	if (cpu >= nr_cpu_ids)
+		return -EAGAIN;
+
+	genpd_unlock(genpd);
+
+	/* Send a IPI to wakeup the selected CPU. */
+	smp_send_reschedule(cpu);
+
+	/* Poll to wait for it to complete the power on sequence. */
+	ret = readx_poll_timeout(genpd_status_on, genpd, is_on, is_on,
+				 GENPD_CPU_ON_POLL_PERIOD_US,
+				 GENPD_CPU_ON_TIMEOUT_US);
+
+	genpd_lock(genpd);
+
+	/* Re-check the status as we have released the lock in between. */
+	if (ret || !genpd_status_on_unlocked(genpd))
+		return -EAGAIN;
+
+	return 0;
+}
+
+static bool genpd_need_alive_cpu(struct generic_pm_domain *genpd,
+				 struct device *dev)
+{
+	if (!genpd_is_cpu_domain(genpd))
+		return false;
+
+	/* This is not for CPU devices as those are managed differently. */
+	if (to_gpd_data(dev->power.subsys_data->domain_data)->cpu >= 0)
+		return false;
+
+	/*
+	 * If the current CPU doesn't belong to the genpd's cpumask, we need to
+	 * wake up one of those idle CPUs to power on the CPU domain correctly.
+	 */
+	return !cpumask_test_cpu(smp_processor_id(), genpd->cpus);
+}
+
 /**
  * genpd_power_on - Restore power to a given PM domain and its parents.
  * @genpd: PM domain to power up.
+ * @dev: The device that needs the PM domain to power on.
  * @depth: nesting count for lockdep.
  *
  * Restore power to @genpd and all of its parents so that it is possible to
  * resume a device belonging to it.
  */
-static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
+static int genpd_power_on(struct generic_pm_domain *genpd, struct device *dev,
+			  unsigned int depth)
 {
 	struct gpd_link *link;
 	int ret = 0;
@@ -1043,6 +1109,10 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
 	if (genpd_status_on_unlocked(genpd))
 		return 0;
 
+	/* Special case for a device attached to a CPU domain. */
+	if (genpd_need_alive_cpu(genpd, dev))
+		return genpd_wakeup_cpu(genpd);
+
 	/* Reflect over the entered idle-states residency for debugfs. */
 	genpd_reflect_residency(genpd);
 
@@ -1057,7 +1127,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
 		genpd_sd_counter_inc(parent);
 
 		genpd_lock_nested(parent, depth + 1);
-		ret = genpd_power_on(parent, depth + 1);
+		ret = genpd_power_on(parent, dev, depth + 1);
 		genpd_unlock(parent);
 
 		if (ret) {
@@ -1307,7 +1377,7 @@ static int genpd_runtime_resume(struct device *dev)
 
 	genpd_lock(genpd);
 	genpd_restore_performance_state(dev, gpd_data->rpm_pstate);
-	ret = genpd_power_on(genpd, 0);
+	ret = genpd_power_on(genpd, dev, 0);
 	genpd_unlock(genpd);
 
 	if (ret)
@@ -3411,7 +3481,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 
 	if (power_on) {
 		genpd_lock(pd);
-		ret = genpd_power_on(pd, 0);
+		ret = genpd_power_on(pd, dev, 0);
 		genpd_unlock(pd);
 	}
 
-- 
2.43.0

Re: [PATCH v2 2/5] pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power on

[Dhruva G]

On 01-09-2026 16:44, Ulf Hansson wrote:
> A driver for a non-CPU device that is attached to a CPU PM domain (the
> genpd has the GENPD_FLAG_CPU_DOMAIN configuration set), is currently not
> able to power on the PM domain. More precisely, to power on a CPU PM domain
> one of its corresponding CPUs needs to be woken up if they are idle.
> 
> The current support for a non-CPU device is that its driver can only
> prevent an already powered on CPU PM domain from being powered off. This
> leads to problems for a driver while probing its device or when it needs to
> call pm_runtime_get_sync() to turn on the power for it. From the driver
> point of view it looks like it all works fine, but when accessing the
> device it may end up with various errors as the device may not be fully
> powered on.
> 
> To fix the behavior for these types of devices, let's adjust the behaviour
> in genpd_power_on() to wake up an idle CPU that belongs to it, in cases
> when it's needed.
> 
> Link: https://lore.kernel.org/all/CAPx+jO-sCierYj8jnoKQHckJG16dOBxnNrsZVYO=38R2cLV8nw@mail.gmail.com/
> Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
> ---
> 
> Changes in v2:
> 	- Rename a function according to Abel's suggestion.
> 
> ---
>  drivers/pmdomain/core.c | 80 ++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 75 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 6ac1ce18fda3..97273ed2f825 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -10,6 +10,7 @@
>  #include <linux/idr.h>
>  #include <linux/kernel.h>
>  #include <linux/io.h>
> +#include <linux/iopoll.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_opp.h>
>  #include <linux/pm_runtime.h>
> @@ -19,11 +20,14 @@
>  #include <linux/slab.h>
>  #include <linux/err.h>
>  #include <linux/sched.h>
> +#include <linux/smp.h>
>  #include <linux/suspend.h>
>  #include <linux/export.h>
>  #include <linux/cpu.h>
>  #include <linux/debugfs.h>
>  
> +#include <trace/events/ipi.h>
> +
>  /* Provides a unique ID for each genpd device */
>  static DEFINE_IDA(genpd_ida);
>  
> @@ -32,7 +36,9 @@ static const struct bus_type genpd_provider_bus_type = {
>  	.name		= "genpd_provider",
>  };
>  
> -#define GENPD_RETRY_MAX_MS	250		/* Approximate */
> +#define GENPD_RETRY_MAX_MS		250		/* Approximate */
> +#define GENPD_CPU_ON_POLL_PERIOD_US	100		/* 100us */
> +#define GENPD_CPU_ON_TIMEOUT_US		5000000		/* 5s */
>  
>  #define GENPD_DEV_CALLBACK(genpd, type, callback, dev)		\
>  ({								\
> @@ -1027,15 +1033,75 @@ static void genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
>  	}
>  }
>  
> +static bool genpd_status_on(struct generic_pm_domain *genpd)
> +{
> +	bool is_on;
> +
> +	genpd_lock(genpd);
> +	is_on = genpd_status_on_unlocked(genpd);
> +	genpd_unlock(genpd);
> +
> +	return is_on;
> +}
> +
> +static int genpd_wakeup_cpu(struct generic_pm_domain *genpd)
> +{
> +	unsigned int cpu;
> +	bool is_on;
> +	int ret;
> +
> +	/* Find the first online CPU in the genpd's cpumask. */
> +	cpu = cpumask_first_and(genpd->cpus, cpu_online_mask);
> +	if (cpu >= nr_cpu_ids)
> +		return -EAGAIN;
> +
> +	genpd_unlock(genpd);
> +
> +	/* Send a IPI to wakeup the selected CPU. */
> +	smp_send_reschedule(cpu);
> +
> +	/* Poll to wait for it to complete the power on sequence. */
> +	ret = readx_poll_timeout(genpd_status_on, genpd, is_on, is_on,
> +				 GENPD_CPU_ON_POLL_PERIOD_US,
> +				 GENPD_CPU_ON_TIMEOUT_US);

How is sleeping here made safe for IRQ-safe consumers and child domains?

For a hypothetical example, consider an IRQ-safe SPI controller in an IRQ-safe child domain D,
whose parent P is a CPU domain. CPU A is outside P, and CPU B belongs to P. Both domains are initially off.

A runtime-resume request on CPU A follows this path in drivers/pmdomain/core.c:

genpd_runtime_resume(SPI device)
-> lock D
-> genpd_power_on(D)
-> lock parent P
-> genpd_power_on(P)
-> genpd_wakeup_cpu(P)

genpd_wakeup_cpu() drops P's lock and sends an IPI to CPU B, but D's spinlock remains held. readx_poll_timeout() 
can then reach usleep_range() while D’s spinlock is still held.

There is also a problem without the child domain: for an IRQ-safe device attached directly to P, __rpm_callback()
leaves interrupts disabled. Dropping P’s lock restores the already-disabled interrupt state, so readx_poll_timeout()
still cannot be used with a nonzero sleep interval and timeout.

I have not reproduced this on a board; this is a hypothetical configuration illustrating the paths.

Is there a restriction elsewhere that prevents either configuration? Otherwise, this wait cannot sleep,
and the parent lock needs to be reacquired with the same nesting depth used by genpd_power_on().



> +
> +	genpd_lock(genpd);
> +
> +	/* Re-check the status as we have released the lock in between. */
> +	if (ret || !genpd_status_on_unlocked(genpd))
> +		return -EAGAIN;
> +
> +	return 0;
> +}
> +
> +static bool genpd_need_alive_cpu(struct generic_pm_domain *genpd,
> +				 struct device *dev)
> +{
> +	if (!genpd_is_cpu_domain(genpd))
> +		return false;
> +
> +	/* This is not for CPU devices as those are managed differently. */
> +	if (to_gpd_data(dev->power.subsys_data->domain_data)->cpu >= 0)
> +		return false;
> +
> +	/*
> +	 * If the current CPU doesn't belong to the genpd's cpumask, we need to
> +	 * wake up one of those idle CPUs to power on the CPU domain correctly.
> +	 */
> +	return !cpumask_test_cpu(smp_processor_id(), genpd->cpus);
> +}
> +
>  /**
>   * genpd_power_on - Restore power to a given PM domain and its parents.
>   * @genpd: PM domain to power up.
> + * @dev: The device that needs the PM domain to power on.
>   * @depth: nesting count for lockdep.
>   *
>   * Restore power to @genpd and all of its parents so that it is possible to
>   * resume a device belonging to it.
>   */
> -static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
> +static int genpd_power_on(struct generic_pm_domain *genpd, struct device *dev,
> +			  unsigned int depth)
>  {
>  	struct gpd_link *link;
>  	int ret = 0;
> @@ -1043,6 +1109,10 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
>  	if (genpd_status_on_unlocked(genpd))
>  		return 0;
>  
> +	/* Special case for a device attached to a CPU domain. */
> +	if (genpd_need_alive_cpu(genpd, dev))
> +		return genpd_wakeup_cpu(genpd);
> +
>  	/* Reflect over the entered idle-states residency for debugfs. */
>  	genpd_reflect_residency(genpd);
>  
> @@ -1057,7 +1127,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
>  		genpd_sd_counter_inc(parent);
>  
>  		genpd_lock_nested(parent, depth + 1);
> -		ret = genpd_power_on(parent, depth + 1);
> +		ret = genpd_power_on(parent, dev, depth + 1);
>  		genpd_unlock(parent);
>  
>  		if (ret) {
> @@ -1307,7 +1377,7 @@ static int genpd_runtime_resume(struct device *dev)
>  
>  	genpd_lock(genpd);
>  	genpd_restore_performance_state(dev, gpd_data->rpm_pstate);
> -	ret = genpd_power_on(genpd, 0);
> +	ret = genpd_power_on(genpd, dev, 0);
>  	genpd_unlock(genpd);
>  
>  	if (ret)
> @@ -3411,7 +3481,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>  
>  	if (power_on) {
>  		genpd_lock(pd);
> -		ret = genpd_power_on(pd, 0);
> +		ret = genpd_power_on(pd, dev, 0);
>  		genpd_unlock(pd);
>  	}
>  

Re: [PATCH v2 2/5] pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power on

[Ulf Hansson]

On Fri, Sep 4, 2026 at 6:26 PM Dhruva G <goledhruva@gmail.com> wrote:
>
> On 01-09-2026 16:44, Ulf Hansson wrote:
> > A driver for a non-CPU device that is attached to a CPU PM domain (the
> > genpd has the GENPD_FLAG_CPU_DOMAIN configuration set), is currently not
> > able to power on the PM domain. More precisely, to power on a CPU PM domain
> > one of its corresponding CPUs needs to be woken up if they are idle.
> >
> > The current support for a non-CPU device is that its driver can only
> > prevent an already powered on CPU PM domain from being powered off. This
> > leads to problems for a driver while probing its device or when it needs to
> > call pm_runtime_get_sync() to turn on the power for it. From the driver
> > point of view it looks like it all works fine, but when accessing the
> > device it may end up with various errors as the device may not be fully
> > powered on.
> >
> > To fix the behavior for these types of devices, let's adjust the behaviour
> > in genpd_power_on() to wake up an idle CPU that belongs to it, in cases
> > when it's needed.
> >
> > Link: https://lore.kernel.org/all/CAPx+jO-sCierYj8jnoKQHckJG16dOBxnNrsZVYO=38R2cLV8nw@mail.gmail.com/
> > Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
> > Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
> > ---
> >
> > Changes in v2:
> >       - Rename a function according to Abel's suggestion.
> >
> > ---
> >  drivers/pmdomain/core.c | 80 ++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 75 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> > index 6ac1ce18fda3..97273ed2f825 100644
> > --- a/drivers/pmdomain/core.c
> > +++ b/drivers/pmdomain/core.c
> > @@ -10,6 +10,7 @@
> >  #include <linux/idr.h>
> >  #include <linux/kernel.h>
> >  #include <linux/io.h>
> > +#include <linux/iopoll.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pm_opp.h>
> >  #include <linux/pm_runtime.h>
> > @@ -19,11 +20,14 @@
> >  #include <linux/slab.h>
> >  #include <linux/err.h>
> >  #include <linux/sched.h>
> > +#include <linux/smp.h>
> >  #include <linux/suspend.h>
> >  #include <linux/export.h>
> >  #include <linux/cpu.h>
> >  #include <linux/debugfs.h>
> >
> > +#include <trace/events/ipi.h>
> > +
> >  /* Provides a unique ID for each genpd device */
> >  static DEFINE_IDA(genpd_ida);
> >
> > @@ -32,7 +36,9 @@ static const struct bus_type genpd_provider_bus_type = {
> >       .name           = "genpd_provider",
> >  };
> >
> > -#define GENPD_RETRY_MAX_MS   250             /* Approximate */
> > +#define GENPD_RETRY_MAX_MS           250             /* Approximate */
> > +#define GENPD_CPU_ON_POLL_PERIOD_US  100             /* 100us */
> > +#define GENPD_CPU_ON_TIMEOUT_US              5000000         /* 5s */
> >
> >  #define GENPD_DEV_CALLBACK(genpd, type, callback, dev)               \
> >  ({                                                           \
> > @@ -1027,15 +1033,75 @@ static void genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
> >       }
> >  }
> >
> > +static bool genpd_status_on(struct generic_pm_domain *genpd)
> > +{
> > +     bool is_on;
> > +
> > +     genpd_lock(genpd);
> > +     is_on = genpd_status_on_unlocked(genpd);
> > +     genpd_unlock(genpd);
> > +
> > +     return is_on;
> > +}
> > +
> > +static int genpd_wakeup_cpu(struct generic_pm_domain *genpd)
> > +{
> > +     unsigned int cpu;
> > +     bool is_on;
> > +     int ret;
> > +
> > +     /* Find the first online CPU in the genpd's cpumask. */
> > +     cpu = cpumask_first_and(genpd->cpus, cpu_online_mask);
> > +     if (cpu >= nr_cpu_ids)
> > +             return -EAGAIN;
> > +
> > +     genpd_unlock(genpd);
> > +
> > +     /* Send a IPI to wakeup the selected CPU. */
> > +     smp_send_reschedule(cpu);
> > +
> > +     /* Poll to wait for it to complete the power on sequence. */
> > +     ret = readx_poll_timeout(genpd_status_on, genpd, is_on, is_on,
> > +                              GENPD_CPU_ON_POLL_PERIOD_US,
> > +                              GENPD_CPU_ON_TIMEOUT_US);
>
> How is sleeping here made safe for IRQ-safe consumers and child domains?
>
> For a hypothetical example, consider an IRQ-safe SPI controller in an IRQ-safe child domain D,
> whose parent P is a CPU domain. CPU A is outside P, and CPU B belongs to P. Both domains are initially off.
>
> A runtime-resume request on CPU A follows this path in drivers/pmdomain/core.c:
>
> genpd_runtime_resume(SPI device)
> -> lock D
> -> genpd_power_on(D)
> -> lock parent P
> -> genpd_power_on(P)
> -> genpd_wakeup_cpu(P)
>
> genpd_wakeup_cpu() drops P's lock and sends an IPI to CPU B, but D's spinlock remains held. readx_poll_timeout()
> can then reach usleep_range() while D’s spinlock is still held.
>
> There is also a problem without the child domain: for an IRQ-safe device attached directly to P, __rpm_callback()
> leaves interrupts disabled. Dropping P’s lock restores the already-disabled interrupt state, so readx_poll_timeout()
> still cannot be used with a nonzero sleep interval and timeout.
>
> I have not reproduced this on a board; this is a hypothetical configuration illustrating the paths.
>
> Is there a restriction elsewhere that prevents either configuration? Otherwise, this wait cannot sleep,
> and the parent lock needs to be reacquired with the same nesting depth used by genpd_power_on().

Good point and thanks for catching this!

As this path is only for CPU PM domains (has GENPD_FLAG_IRQ_SAFE and
GENPD_FLAG_CPU_DOMAIN bits set), this is solved by converting to the
atomic polling helpers. I am cooking a new version!

[...]

Kind regards
Uffe

[PATCH v2 3/5] pmdomain: core: Add a genpd config to support unknown initial status

[Ulf Hansson]

It's not always possible for a genpd provider to know the initial status
for its corresponding PM domain(s). To register the PM domain in a safe
state, the genpd provider driver may therefore have to initialize the
genpd's status to be powered off, as a way to prevent the PM domain from
being used when it actually could be powered off.

In these cases we may end up to power on a PM domain through the genpd
subsystem, while from the HW point of view it may already be powered on.
Under these circumstances, it may also be required to keep the PM domain
powered on until all the consumer devices have been probed. In other words,
until the ->sync_state() callback for the genpd provider in question have
been called.

To support this behaviour for a genpd provider, let's introduce a new genpd
configuration, GENPD_FLAG_POWER_UNKNOWN.

Reported-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
Link: https://lore.kernel.org/all/20260811-domain_off_ss3-v1-0-6a0a0fc023f5@oss.qualcomm.com/
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
---

Changes in v2:
	- Rename the config to GENPD_FLAG_POWER_UNKNOWN.

---
 drivers/pmdomain/core.c   | 6 +++++-
 include/linux/pm_domain.h | 9 +++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 97273ed2f825..ab6110885175 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -189,6 +189,7 @@ static const struct genpd_lock_ops genpd_raw_spin_ops = {
 #define genpd_is_dev_name_fw(genpd)	(genpd->flags & GENPD_FLAG_DEV_NAME_FW)
 #define genpd_is_no_sync_state(genpd)	(genpd->flags & GENPD_FLAG_NO_SYNC_STATE)
 #define genpd_is_no_stay_on(genpd)	(genpd->flags & GENPD_FLAG_NO_STAY_ON)
+#define genpd_is_power_unknown(genpd)	(genpd->flags & GENPD_FLAG_POWER_UNKNOWN)
 
 static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
 		const struct generic_pm_domain *genpd)
@@ -2446,7 +2447,10 @@ static void genpd_lock_init(struct generic_pm_domain *genpd)
 #ifdef CONFIG_PM_GENERIC_DOMAINS_OF
 static void genpd_set_stay_on(struct generic_pm_domain *genpd, bool is_off)
 {
-	genpd->stay_on = !genpd_is_no_stay_on(genpd) && !is_off;
+	if (genpd_is_power_unknown(genpd))
+		genpd->stay_on = is_off;
+	else
+		genpd->stay_on = !genpd_is_no_stay_on(genpd) && !is_off;
 }
 #else
 static void genpd_set_stay_on(struct generic_pm_domain *genpd, bool is_off)
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index f925614aebdb..14e0e346c610 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -121,6 +121,14 @@ struct dev_pm_domain_list {
  *				powered-off until the ->sync_state() callback is
  *				invoked. This flag informs genpd to allow a
  *				power-off without waiting for ->sync_state().
+ *
+ * GENPD_FLAG_POWER_UNKNOWN:	Use this flag to inform	genpd that its initial
+ *				status for the PM domain is set to powered off,
+ *				which may not correctly reflect the state of the
+ *				HW, as it's unknown. If the PM domain becomes
+ *				powered on during boot, genpd will prevent it
+ *				from being powered off until the ->sync_state
+ *				callback is invoked for it.
  */
 #define GENPD_FLAG_PM_CLK	 (1U << 0)
 #define GENPD_FLAG_IRQ_SAFE	 (1U << 1)
@@ -133,6 +141,7 @@ struct dev_pm_domain_list {
 #define GENPD_FLAG_DEV_NAME_FW	 (1U << 8)
 #define GENPD_FLAG_NO_SYNC_STATE (1U << 9)
 #define GENPD_FLAG_NO_STAY_ON	 (1U << 10)
+#define GENPD_FLAG_POWER_UNKNOWN (1U << 11)
 
 enum gpd_status {
 	GENPD_STATE_ON = 0,	/* PM domain is on */
-- 
2.43.0

[PATCH v2 4/5] cpuidle: psci: Initialize the PM domains in powered off state for OSI

[Ulf Hansson]

At the point when the PM domain and the topology are registered through the
genpd subsystem, it's not really known whether corresponding CPUs are
online and thus if the PM domain should be initialized as powered on or
not. Instead this information becomes available when the CPU devices gets
attached to their respective PM domain through dt_idle_attach_cpu().

This is a problem when using PSCI OS-initiated mode, as we may end up with
a PM domain that has the genpd's status indicating it to be powered on,
while it in fact may not be the case. In the less severe scenario, this
leads to selecting a shallower domain idle state for the PM domain than
necessary. A more critical problem is when a non-CPU device shares the PM
domain, leading to their corresponding drivers not being able to trust the
status of it.

Let's fix these problems by initializing the state for the genpd's to be
powered off and in the deepest possible domain idle state, when using
OS-initiated mode. The support for ->sync_state() is maintained by setting
the GENPD_FLAG_POWER_UNKNOWN for the genpds in question.

Reported-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
Link: https://lore.kernel.org/all/20260811-domain_off_ss3-v1-0-6a0a0fc023f5@oss.qualcomm.com/
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
---

Changes in v2:
	- Fix a bug in the call to pm_genpd_init().

---
 drivers/cpuidle/cpuidle-psci-domain.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index b9e4ad7d43a3..4d8c63d329c2 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -68,7 +68,8 @@ static int psci_pd_init(struct device_node *np, bool use_osi)
 	 */
 	if (use_osi) {
 		pd->power_off = psci_pd_power_off;
-		pd->flags |= GENPD_FLAG_ACTIVE_WAKEUP;
+		pd->flags |= GENPD_FLAG_ACTIVE_WAKEUP | GENPD_FLAG_POWER_UNKNOWN;
+		pd->state_idx = pd->state_count ? pd->state_count - 1 : 0;
 		if (IS_ENABLED(CONFIG_PREEMPT_RT))
 			pd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
 	} else {
@@ -78,7 +79,7 @@ static int psci_pd_init(struct device_node *np, bool use_osi)
 	/* Use governor for CPU PM domains if it has some states to manage. */
 	pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
 
-	ret = pm_genpd_init(pd, pd_gov, false);
+	ret = pm_genpd_init(pd, pd_gov, use_osi);
 	if (ret)
 		goto free_pd_prov;
 
-- 
2.43.0

[PATCH v2 5/5] cpuidle: psci: Move initialization a bit earlier in the boot sequence

[Ulf Hansson]

When using PSCI OS-initiated mode along with the cpuidle-psci-domain driver
it's of great benefit to attach the CPU devices to their CPU PM domains as
soon as possible, as other non-CPU devices sharing the same PM domains
depends on it to allow their devices to be probed.

Let's therefore move to a subsys_initcall, which should be soon enough
after the cpuidle-psci-domain have initialized the PM domain topology.

Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
---

Changes in v2:
	- New patch.

---
 drivers/cpuidle/cpuidle-psci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index b250d0dde760..0187d6a9096a 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -479,4 +479,4 @@ static int __init psci_idle_init(void)
 
 	return 0;
 }
-device_initcall(psci_idle_init);
+subsys_initcall(psci_idle_init);
-- 
2.43.0

Re: [PATCH v2 5/5] cpuidle: psci: Move initialization a bit earlier in the boot sequence

[Abel Vesa]

On 26-09-01 13:14:08, Ulf Hansson wrote:
> When using PSCI OS-initiated mode along with the cpuidle-psci-domain driver
> it's of great benefit to attach the CPU devices to their CPU PM domains as
> soon as possible, as other non-CPU devices sharing the same PM domains
> depends on it to allow their devices to be probed.
> 
> Let's therefore move to a subsys_initcall, which should be soon enough
> after the cpuidle-psci-domain have initialized the PM domain topology.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>

Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>

Re: [PATCH v2 0/5] pmdomain/cpuidle-psci: Fix behaviours for CPU PM domains

[Yuanfang Zhang]

Tested-by: Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>

On 9/1/2026 7:14 PM, Ulf Hansson wrote:
> From: Ulf Hansson <ulfh@kernel.org>
> 
> This series fixes a couple of different, but highly related problems, when
> dealing with CPU PM domains. More details are available in the commit messages
> for each patch.
> 
> Note that, this series is a follow up to fix problems that have been pointed
> out in a series [1] from Yuanfang Zhang (Qcom), to add support for new
> components for the arm coresight subsystem.
> 
> Changes in v2:
> 	- Dropped the RFC.
> 	- See updates in the changelog for each patch.
> 
> Kind regards
> Uffe
> 
> [1]
> [PATCH v2 00/12] coresight: Add CPU cluster funnel/replicator/tmc support
> https://lore.kernel.org/all/20251218-cpu_cluster_component_pm-v2-0-2335a6ae62a0@oss.qualcomm.com/#r
> 
> 
> Ulf Hansson (5):
>   pmdomain: core: Rename genpd_status_on()
>   pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power
>     on
>   pmdomain: core: Add a genpd config to support unknown initial status
>   cpuidle: psci: Initialize the PM domains in powered off state for OSI
>   cpuidle: psci: Move initialization a bit earlier in the boot sequence
> 
>  drivers/cpuidle/cpuidle-psci-domain.c |   5 +-
>  drivers/cpuidle/cpuidle-psci.c        |   2 +-
>  drivers/pmdomain/core.c               | 111 +++++++++++++++++++++-----
>  include/linux/pm_domain.h             |   9 +++
>  4 files changed, 106 insertions(+), 21 deletions(-)
>