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authorUlf Hansson <ulf.hansson@linaro.org>2013-11-08 06:13:51 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-11-12 23:20:30 +0100
commitea309944e226d655d7d4adca9623c575ba786bbe (patch)
treed5626cad04dcea315cc938a18478b69d97ffb2b4 /Documentation/power
parentbaab52ded242c35a2290e1fa82e0cc147d0d8c1a (diff)
downloadlinux-linaro-stable-ea309944e226d655d7d4adca9623c575ba786bbe.tar.gz
PM / Runtime: Update documentation around probe|remove|suspend
PM core and driver core has changed some behavior regarding use of runtime PM. Update the documentation accordingly. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/power')
-rw-r--r--Documentation/power/runtime_pm.txt14
1 files changed, 6 insertions, 8 deletions
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 0f54333b0ff2..b6ce00b2be9a 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -547,13 +547,11 @@ helper functions described in Section 4. In that case, pm_runtime_resume()
should be used. Of course, for this purpose the device's runtime PM has to be
enabled earlier by calling pm_runtime_enable().
-If the device bus type's or driver's ->probe() callback runs
-pm_runtime_suspend() or pm_runtime_idle() or their asynchronous counterparts,
-they will fail returning -EAGAIN, because the device's usage counter is
-incremented by the driver core before executing ->probe(). Still, it may be
-desirable to suspend the device as soon as ->probe() has finished, so the driver
-core uses pm_runtime_put_sync() to invoke the subsystem-level idle callback for
-the device at that time.
+It may be desirable to suspend the device once ->probe() has finished.
+Therefore the driver core uses the asyncronous pm_request_idle() to submit a
+request to execute the subsystem-level idle callback for the device at that
+time. A driver that makes use of the runtime autosuspend feature, may want to
+update the last busy mark before returning from ->probe().
Moreover, the driver core prevents runtime PM callbacks from racing with the bus
notifier callback in __device_release_driver(), which is necessary, because the
@@ -656,7 +654,7 @@ out the following operations:
__pm_runtime_disable() with 'false' as the second argument for every device
right before executing the subsystem-level .suspend_late() callback for it.
- * During system resume it calls pm_runtime_enable() and pm_runtime_put_sync()
+ * During system resume it calls pm_runtime_enable() and pm_runtime_put()
for every device right after executing the subsystem-level .resume_early()
callback and right after executing the subsystem-level .resume() callback
for it, respectively.