[PATCH 2/4] pmdomain: core: Prepare boot performance floors before system suspend

[Abel Vesa]

A system suspend can occur before a provider has received sync_state().
If a domain has not been used through runtime PM, its boot performance
floor may not have been applied when genpd_sync_power_on() enables it
during resume-noirq.

Prepare boot performance floors from genpd_prepare(), where performance
callbacks may sleep. Walk the parent hierarchy even when the device's
own domain has no boot floor: a parent without direct consumers would
otherwise miss preparation entirely. Take parent locks in the existing
child-to-parent order and propagate preparation failures to the PM core.

Also retain boot power protection in genpd_sync_power_off() for domains
with a boot performance floor. This prevents the system-sleep path from
withdrawing their power vote while boot protection remains active.

Keep performance programming out of resume-noirq. Domains with their
floor already satisfied do not need another performance update, and
no floor is imposed after sync_state() releases boot protection.

Assisted-by: LLM
Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxxxxxxxx>
---
 drivers/pmdomain/core.c | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 6f2b406ce049..4ff55175d899 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -1538,7 +1538,9 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
 {
 	struct gpd_link *link;
 
-	if (!genpd_status_on_unlocked(genpd) || genpd_is_always_on(genpd))
+	if (!genpd_status_on_unlocked(genpd) || genpd_is_always_on(genpd) ||
+	    (genpd_is_power_unknown(genpd) && genpd->stay_on &&
+	     genpd->boot_performance_state))
 		return;
 
 	if (genpd->suspended_count != genpd->device_count
@@ -1623,6 +1625,31 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
 	genpd->status = GENPD_STATE_ON;
 }
 
+/* Called with the domain lock held, before entering noirq. */
+static int genpd_prepare_boot_performance(struct generic_pm_domain *genpd,
+					 unsigned int depth)
+{
+	struct gpd_link *link;
+	int ret;
+
+	/* Parents may need a boot floor even when this domain does not. */
+	list_for_each_entry(link, &genpd->child_links, child_node) {
+		struct generic_pm_domain *parent = link->parent;
+
+		genpd_lock_nested(parent, depth + 1);
+		ret = genpd_prepare_boot_performance(parent, depth + 1);
+		genpd_unlock(parent);
+		if (ret)
+			return ret;
+	}
+
+	if (genpd_needs_boot_performance_state(genpd))
+		return _genpd_set_performance_state(genpd,
+						   genpd->performance_state, depth);
+
+	return 0;
+}
+
 /**
  * genpd_prepare - Start power transition of a device in a PM domain.
  * @dev: Device to start the transition of.
@@ -1644,6 +1671,12 @@ static int genpd_prepare(struct device *dev)
 		return -EINVAL;
 
 	genpd_lock(genpd);
+	/* Performance callbacks may sleep; prepare the hierarchy before noirq. */
+	ret = genpd_prepare_boot_performance(genpd, 0);
+	if (ret) {
+		genpd_unlock(genpd);
+		return ret;
+	}
 	genpd->prepared_count++;
 	genpd_unlock(genpd);
 

-- 
2.54.0