[PATCH] PM / Domains: allow domain idle states to be disabled

[Lina Iyer <ilina@codeaurora.org>]

In order to debug critical domain and device power issues, it may be
necessary to disallow certain idle states at runtime. Let the device
disallow a domain idle state before suspending.The domain governor shall
check for the 'disabled' flag while determining the domain idle state.

Signed-off-by: Lina Iyer <ilina@codeaurora.org>
---
 drivers/base/power/domain.c          | 30 ++++++++++++++++++++++++++++
 drivers/base/power/domain_governor.c |  3 +++
 include/linux/pm_domain.h            |  7 +++++++
 3 files changed, 40 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 191539a8e06d..e4e7ab75bdea 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1926,6 +1926,36 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 }
 EXPORT_SYMBOL_GPL(pm_genpd_remove_subdomain);
 
+/**
+ * dev_pm_genpd_disable_idle_state - Disallow a PM domain's idle state
+ *
+ * @dev: device attached to the PM domain
+ * @idx: index of the PM domain's idle state to be disabled
+ * @disable: enable/disable idle state
+ *
+ * Allow a PM domain's idle state to be disabled. Disabled idle states will
+ * be ignored by the domain governor when entering idle. Devices would
+ * invoke this before calling runtime suspend.
+ */
+int dev_pm_genpd_disable_idle_state(struct device *dev, unsigned int idx, bool disable)
+{
+	struct generic_pm_domain *genpd;
+
+	genpd = dev_to_genpd_safe(dev);
+	if (!genpd)
+		return -ENODEV;
+
+	if (idx >= genpd->state_count)
+		return -EINVAL;
+
+	genpd_lock(genpd);
+	genpd->states[idx].disabled = disable;
+	genpd_unlock(genpd);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dev_pm_genpd_disable_idle_state);
+
 static void genpd_free_default_power_state(struct genpd_power_state *states,
 					   unsigned int state_count)
 {
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
index 2afb7fa90d5d..8decd17c5a6a 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -175,6 +175,9 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
 	s64 min_off_time_ns;
 	s64 off_on_time_ns;
 
+	if (genpd->states[state].disabled)
+		return false;
+
 	off_on_time_ns = genpd->states[state].power_off_latency_ns +
 		genpd->states[state].power_on_latency_ns;
 
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index a41aea9d1c06..3d251b5b461a 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -101,6 +101,7 @@ struct genpd_power_state {
 	struct fwnode_handle *fwnode;
 	ktime_t idle_time;
 	void *data;
+	bool disabled;
 };
 
 struct genpd_lock_ops;
@@ -233,6 +234,7 @@ int dev_pm_genpd_add_notifier(struct device *dev, struct notifier_block *nb);
 int dev_pm_genpd_remove_notifier(struct device *dev);
 void genpd_enable_next_wakeup(struct generic_pm_domain *genpd, bool enable);
 int dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next);
+int dev_pm_genpd_disable_idle_state(struct device *dev, unsigned int idx, bool disable);
 
 extern struct dev_power_governor simple_qos_governor;
 extern struct dev_power_governor pm_domain_always_on_gov;
@@ -300,6 +302,11 @@ static inline int dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next)
 	return -EOPNOTSUPP;
 }
 
+static inline int dev_pm_genpd_disable_idle_state(struct device *dev, unsigned int idx, bool disable)
+{
+	return -EOPNOTSUPP;
+}
+
 #define simple_qos_governor		(*(struct dev_power_governor *)(NULL))
 #define pm_domain_always_on_gov		(*(struct dev_power_governor *)(NULL))
 #endif
-- 
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