===================================================================
@@ -505,6 +505,7 @@ static int legacy_resume(struct device *
static int device_resume(struct device *dev, pm_message_t state, bool async)
{
int error = 0;
+ bool put = false;
TRACE_DEVICE(dev);
TRACE_RESUME(0);
@@ -521,6 +522,9 @@ static int device_resume(struct device *
if (!dev->power.is_suspended)
goto Unlock;
+ pm_runtime_enable(dev);
+ put = true;
+
if (dev->pm_domain) {
pm_dev_dbg(dev, state, "power domain ");
error = pm_op(dev, &dev->pm_domain->ops, state);
@@ -563,6 +567,10 @@ static int device_resume(struct device *
complete_all(&dev->power.completion);
TRACE_RESUME(error);
+
+ if (put)
+ pm_runtime_put_sync(dev);
+
return error;
}
@@ -843,16 +851,22 @@ static int __device_suspend(struct devic
int error = 0;
dpm_wait_for_children(dev, async);
- device_lock(dev);
if (async_error)
- goto Unlock;
+ return 0;
+
+ pm_runtime_get_noresume(dev);
+ if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
+ pm_wakeup_event(dev, 0);
if (pm_wakeup_pending()) {
+ pm_runtime_put_sync(dev);
async_error = -EBUSY;
- goto Unlock;
+ return 0;
}
+ device_lock(dev);
+
if (dev->pm_domain) {
pm_dev_dbg(dev, state, "power domain ");
error = pm_op(dev, &dev->pm_domain->ops, state);
@@ -890,12 +904,15 @@ static int __device_suspend(struct devic
End:
dev->power.is_suspended = !error;
- Unlock:
device_unlock(dev);
complete_all(&dev->power.completion);
- if (error)
+ if (error) {
+ pm_runtime_put_sync(dev);
async_error = error;
+ } else if (dev->power.is_suspended) {
+ __pm_runtime_disable(dev, false);
+ }
return error;
}
===================================================================
@@ -567,6 +567,11 @@ this is:
pm_runtime_set_active(dev);
pm_runtime_enable(dev);
+The PM core always increments the run-time usage counter before calling the
+->suspend() callback and decrements it after calling the ->resume() callback.
+Hence disabling run-time PM temporarily like this will not cause any run-time
+suspend callbacks to be lost.
+
On some systems, however, system sleep is not entered through a global firmware
or hardware operation. Instead, all hardware components are put into low-power
states directly by the kernel in a coordinated way. Then, the system sleep
@@ -579,6 +584,20 @@ place (in particular, if the system is n
be more efficient to leave the devices that had been suspended before the system
suspend began in the suspended state.
+The PM core does its best to reduce the probability of race conditions between
+the runtime PM and system suspend/resume (and hibernation) callbacks by carrying
+out the following operations:
+
+ * During system suspend it calls pm_runtime_get_noresume() and
+ pm_runtime_barrier() for every device right before executing the
+ subsystem-level .suspend() callback for it. In addition to that it calls
+ pm_runtime_disable() for every device right after executing the
+ subsystem-level .suspend() callback for it.
+
+ * During system resume it calls pm_runtime_enable() and pm_runtime_put_sync()
+ for every device right before and right after executing the subsystem-level
+ .resume() callback for it, respectively.
+
7. Generic subsystem callbacks
Subsystems may wish to conserve code space by using the set of generic power