From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
If device_prepare() runs on a device that has never had runtime
PM enabled so far, it may reasonably assume that runtime PM will
not be enabled for that device during the system suspend-resume
cycle currently in progress, but this has never been guaranteed.
To verify this assumption, make device_prepare() arrange for
triggering a device warning accompanied by a call trace dump if
runtime PM is enabled for such a device after it has returned.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
v1 -> v2: Fix a typo in a message and remove an unrelated change (Ulf).
---
drivers/base/power/main.c | 9 +++++++++
drivers/base/power/runtime.c | 24 ++++++++++++++++++++++++
include/linux/pm.h | 1 +
include/linux/pm_runtime.h | 4 ++++
4 files changed, 38 insertions(+)
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1109,6 +1109,8 @@
device_unlock(dev);
out:
+ /* If enabling runtime PM for the device is blocked, unblock it. */
+ pm_runtime_unblock(dev);
pm_runtime_put(dev);
}
@@ -1815,6 +1817,13 @@
* it again during the complete phase.
*/
pm_runtime_get_noresume(dev);
+ /*
+ * If runtime PM is disabled for the device at this point and it has
+ * never been enabled so far, it should not be enabled until this system
+ * suspend-resume cycle is complete, so prepare to trigger a warning on
+ * subsequent attempts to enable it.
+ */
+ pm_runtime_block_if_disabled(dev);
if (dev->power.syscore)
return 0;
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1460,6 +1460,26 @@
}
EXPORT_SYMBOL_GPL(pm_runtime_barrier);
+void pm_runtime_block_if_disabled(struct device *dev)
+{
+ spin_lock_irq(&dev->power.lock);
+
+ if (dev->power.disable_depth && dev->power.last_status == RPM_INVALID)
+ dev->power.last_status = RPM_BLOCKED;
+
+ spin_unlock_irq(&dev->power.lock);
+}
+
+void pm_runtime_unblock(struct device *dev)
+{
+ spin_lock_irq(&dev->power.lock);
+
+ if (dev->power.last_status == RPM_BLOCKED)
+ dev->power.last_status = RPM_INVALID;
+
+ spin_unlock_irq(&dev->power.lock);
+}
+
void __pm_runtime_disable(struct device *dev, bool check_resume)
{
spin_lock_irq(&dev->power.lock);
@@ -1518,6 +1538,10 @@
if (--dev->power.disable_depth > 0)
goto out;
+ if (dev->power.last_status == RPM_BLOCKED) {
+ dev_warn(dev, "Attempt to enable runtime PM when it is blocked\n");
+ dump_stack();
+ }
dev->power.last_status = RPM_INVALID;
dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -597,6 +597,7 @@
RPM_RESUMING,
RPM_SUSPENDED,
RPM_SUSPENDING,
+ RPM_BLOCKED,
};
/*
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -77,6 +77,8 @@
extern int pm_schedule_suspend(struct device *dev, unsigned int delay);
extern int __pm_runtime_set_status(struct device *dev, unsigned int status);
extern int pm_runtime_barrier(struct device *dev);
+extern void pm_runtime_block_if_disabled(struct device *dev);
+extern void pm_runtime_unblock(struct device *dev);
extern void pm_runtime_enable(struct device *dev);
extern void __pm_runtime_disable(struct device *dev, bool check_resume);
extern void pm_runtime_allow(struct device *dev);
@@ -271,6 +273,8 @@
static inline int __pm_runtime_set_status(struct device *dev,
unsigned int status) { return 0; }
static inline int pm_runtime_barrier(struct device *dev) { return 0; }
+static inline void pm_runtime_block_if_disabled(struct device *dev) {}
+static inline void pm_runtime_unblock(struct device *dev) {}
static inline void pm_runtime_enable(struct device *dev) {}
static inline void __pm_runtime_disable(struct device *dev, bool c) {}
static inline void pm_runtime_allow(struct device *dev) {}
