PM / Runtime: Respect autosuspend when idle triggers suspend

For devices which don't have a .runtime_idle() callback or if it
returns 0, rpm_idle() will end up in triggering a call to
rpm_suspend(), thus trying to carry out a runtime suspend directly
from runtime_idle().

In the above situation we want to respect devices which has enabled
autosuspend, we therfore append the flag sent to rpm_suspend with
RPM_AUTO.

Do note that drivers still needs to update the device last busy mark,
to control the delay for this circumstance.

Updated runtime PM documentation accordingly.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 268a35097578..72e00e66ecc5 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -258,7 +258,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
  * Check if the device's runtime PM status allows it to be suspended.  If
  * another idle notification has been started earlier, return immediately.  If
  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
- * run the ->runtime_idle() callback directly.
+ * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
+ * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
  *
  * This function must be called under dev->power.lock with interrupts disabled.
  */
@@ -331,7 +332,7 @@ static int rpm_idle(struct device *dev, int rpmflags)
 
  out:
         trace_rpm_return_int(dev, _THIS_IP_, retval);
-        return retval ? retval : rpm_suspend(dev, rpmflags);
+        return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 }
 
 /**