[PATCH V2] PM / Runtime: Respect autosuspend when idle triggers suspend

[Ulf Hansson <ulf.hansson@linaro.org>]

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 driver's still needs to update the device last busy mark,
to control the delay for this circumstance.

Updated runtime PM documentation accordingly.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Rob Landley <rob@landley.net>
Cc: Chris Ball <cjb@laptop.org>
Cc: linux-mmc@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 Documentation/power/runtime_pm.txt |   13 +++++++------
 drivers/base/power/runtime.c       |    6 ++++--
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 71d8fe4..236d9f4 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -145,11 +145,12 @@ The action performed by the idle callback is totally dependent on the subsystem
 if the device can be suspended (i.e. if all of the conditions necessary for
 suspending the device are satisfied) and to queue up a suspend request for the
 device in that case.  If there is no idle callback, or if the callback returns
-0, then the PM core will attempt to carry out a runtime suspend of the device;
-in essence, it will call pm_runtime_suspend() directly.  To prevent this (for
-example, if the callback routine has started a delayed suspend), the routine
-should return a non-zero value.  Negative error return codes are ignored by the
-PM core.
+0, then the PM core will attempt to carry out a runtime suspend of the device,
+also respecting devices configured for autosuspend. In essence it means a call
+to pm_runtime_autosuspend(). Do note that driver's still needs to update the
+device last busy mark (pm_runtime_mark_last_busy), to control the delay under
+this circumstance. To prevent this, the routine must return a non-zero value.
+Negative error return codes are ignored by the PM core.
 
 The helper functions provided by the PM core, described in Section 4, guarantee
 that the following constraints are met with respect to runtime PM callbacks for
@@ -308,7 +309,7 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
     - execute the subsystem-level idle callback for the device; returns an
       error code on failure, where -EINPROGRESS means that ->runtime_idle() is
       already being executed; if there is no callback or the callback returns 0
-      then run pm_runtime_suspend(dev) and return its result
+      then run pm_runtime_autosuspend(dev) and return its result
 
   int pm_runtime_suspend(struct device *dev);
     - execute the subsystem-level suspend callback for the device; returns 0 on
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 268a350..e6867d4 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -258,7 +258,9 @@ 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, run rpm_suspend with RPM_AUTO flag to
+ * respect drivers using autosuspend.
  *
  * This function must be called under dev->power.lock with interrupts disabled.
  */
@@ -331,7 +333,7 @@ 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);
 }
 
 /**
-- 
1.7.9.5