PM / runtime: print error when activating a child to unactive parent

The code currently silently bails out with -EBUSY if you try to
activate a child to an inactive parent.

This typically happens when you have a runtime suspended parent
and runtime resume your child, but forgot to set .ignore_children
on the parent to true with pm_suspend_ignore_children(dev).

Silently ignoring this error is not good as it gives rise to
other strange behaviour like double-resume of devices after
silently bailing out of the .runtime_resume() callback.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b74690418504..e7ee8293055b 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1045,10 +1045,14 @@ int __pm_runtime_set_status(struct device *dev, unsigned int status)
                  */
                 if (!parent->power.disable_depth
                     && !parent->power.ignore_children
-                    && parent->power.runtime_status != RPM_ACTIVE)
+                    && parent->power.runtime_status != RPM_ACTIVE) {
+                        dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
+                                dev_name(dev),
+                                dev_name(parent));
                         error = -EBUSY;
-                else if (dev->power.runtime_status == RPM_SUSPENDED)
+                } else if (dev->power.runtime_status == RPM_SUSPENDED) {
                         atomic_inc(&parent->power.child_count);
+                }
 
                 spin_unlock(&parent->power.lock);