PM / Runtime: Add synchronous runtime interface for interrupt handlers (v3)
This patch (as1431c) makes the synchronous runtime-PM interface
suitable for use in interrupt handlers. Subsystems can call the new
pm_runtime_irq_safe() function to tell the PM core that a device's
runtime_suspend and runtime_resume callbacks should be invoked with
interrupts disabled and the spinlock held. This permits the
pm_runtime_get_sync() and the new pm_runtime_put_sync_suspend()
routines to be called from within interrupt handlers.
When a device is declared irq-safe in this way, the PM core increments
the parent's usage count, so the parent will never be runtime
suspended. This prevents difficult situations in which an irq-safe
device can't resume because it is forced to wait for its non-irq-safe
parent.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 02c652b..656493a 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -250,13 +250,16 @@
if (!cb)
return -ENOSYS;
- spin_unlock_irq(&dev->power.lock);
+ if (dev->power.irq_safe) {
+ retval = cb(dev);
+ } else {
+ spin_unlock_irq(&dev->power.lock);
- retval = cb(dev);
+ retval = cb(dev);
- spin_lock_irq(&dev->power.lock);
+ spin_lock_irq(&dev->power.lock);
+ }
dev->power.runtime_error = retval;
-
return retval;
}
@@ -404,7 +407,7 @@
goto out;
}
- if (parent && !parent->power.ignore_children) {
+ if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
spin_unlock_irq(&dev->power.lock);
pm_request_idle(parent);
@@ -527,10 +530,13 @@
if (!parent && dev->parent) {
/*
- * Increment the parent's resume counter and resume it if
- * necessary.
+ * Increment the parent's usage counter and resume it if
+ * necessary. Not needed if dev is irq-safe; then the
+ * parent is permanently resumed.
*/
parent = dev->parent;
+ if (dev->power.irq_safe)
+ goto skip_parent;
spin_unlock(&dev->power.lock);
pm_runtime_get_noresume(parent);
@@ -553,6 +559,7 @@
goto out;
goto repeat;
}
+ skip_parent:
if (dev->power.no_callbacks)
goto no_callback; /* Assume success. */
@@ -584,7 +591,7 @@
rpm_idle(dev, RPM_ASYNC);
out:
- if (parent) {
+ if (parent && !dev->power.irq_safe) {
spin_unlock_irq(&dev->power.lock);
pm_runtime_put(parent);
@@ -1065,7 +1072,6 @@
* Set the power.no_callbacks flag, which tells the PM core that this
* device is power-managed through its parent and has no run-time PM
* callbacks of its own. The run-time sysfs attributes will be removed.
- *
*/
void pm_runtime_no_callbacks(struct device *dev)
{
@@ -1078,6 +1084,27 @@
EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
/**
+ * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
+ * @dev: Device to handle
+ *
+ * Set the power.irq_safe flag, which tells the PM core that the
+ * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
+ * always be invoked with the spinlock held and interrupts disabled. It also
+ * causes the parent's usage counter to be permanently incremented, preventing
+ * the parent from runtime suspending -- otherwise an irq-safe child might have
+ * to wait for a non-irq-safe parent.
+ */
+void pm_runtime_irq_safe(struct device *dev)
+{
+ if (dev->parent)
+ pm_runtime_get_sync(dev->parent);
+ spin_lock_irq(&dev->power.lock);
+ dev->power.irq_safe = 1;
+ spin_unlock_irq(&dev->power.lock);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
+
+/**
* update_autosuspend - Handle a change to a device's autosuspend settings.
* @dev: Device to handle.
* @old_delay: The former autosuspend_delay value.
@@ -1199,4 +1226,6 @@
/* Change the status back to 'suspended' to match the initial status. */
if (dev->power.runtime_status == RPM_ACTIVE)
pm_runtime_set_suspended(dev);
+ if (dev->power.irq_safe && dev->parent)
+ pm_runtime_put_sync(dev->parent);
}