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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-05-16 02:46:50 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-05-16 23:15:44 +0200
commitaae4518b3124b29f8dc81c829c704fd2df72e98b (patch)
tree6ab2d44ce8282838d33450e0895e8ca88ac0abcf /include/linux/pm_runtime.h
parentf6514be5fe7fe796041b673bad769510414ff2b9 (diff)
downloadlwn-aae4518b3124b29f8dc81c829c704fd2df72e98b.tar.gz
lwn-aae4518b3124b29f8dc81c829c704fd2df72e98b.zip
PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily
Currently, some subsystems (e.g. PCI and the ACPI PM domain) have to resume all runtime-suspended devices during system suspend, mostly because those devices may need to be reprogrammed due to different wakeup settings for system sleep and for runtime PM. For some devices, though, it's OK to remain in runtime suspend throughout a complete system suspend/resume cycle (if the device was in runtime suspend at the start of the cycle). We would like to do this whenever possible, to avoid the overhead of extra power-up and power-down events. However, problems may arise because the device's descendants may require it to be at full power at various points during the cycle. Therefore the most straightforward way to do this safely is if the device and all its descendants can remain runtime suspended until the complete stage of system resume. To this end, introduce a new device PM flag, power.direct_complete and modify the PM core to use that flag as follows. If the ->prepare() callback of a device returns a positive number, the PM core will regard that as an indication that it may leave the device runtime-suspended. It will then check if the system power transition in progress is a suspend (and not hibernation in particular) and if the device is, indeed, runtime-suspended. In that case, the PM core will set the device's power.direct_complete flag. Otherwise it will clear power.direct_complete for the device and it also will later clear it for the device's parent (if there's one). Next, the PM core will not invoke the ->suspend() ->suspend_late(), ->suspend_irq(), ->resume_irq(), ->resume_early(), or ->resume() callbacks for all devices having power.direct_complete set. It will invoke their ->complete() callbacks, however, and those callbacks are then responsible for resuming the devices as appropriate, if necessary. For example, in some cases they may need to queue up runtime resume requests for the devices using pm_request_resume(). Changelog partly based on an Alan Stern's description of the idea (http://marc.info/?l=linux-pm&m=139940466625569&w=2). Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Alan Stern <stern@rowland.harvard.edu>
Diffstat (limited to 'include/linux/pm_runtime.h')
-rw-r--r--include/linux/pm_runtime.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 2a5897a4afbc..43fd6716f662 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -101,6 +101,11 @@ static inline bool pm_runtime_status_suspended(struct device *dev)
return dev->power.runtime_status == RPM_SUSPENDED;
}
+static inline bool pm_runtime_suspended_if_enabled(struct device *dev)
+{
+ return pm_runtime_status_suspended(dev) && dev->power.disable_depth == 1;
+}
+
static inline bool pm_runtime_enabled(struct device *dev)
{
return !dev->power.disable_depth;
@@ -150,6 +155,7 @@ static inline void device_set_run_wake(struct device *dev, bool enable) {}
static inline bool pm_runtime_suspended(struct device *dev) { return false; }
static inline bool pm_runtime_active(struct device *dev) { return true; }
static inline bool pm_runtime_status_suspended(struct device *dev) { return false; }
+static inline bool pm_runtime_suspended_if_enabled(struct device *dev) { return false; }
static inline bool pm_runtime_enabled(struct device *dev) { return false; }
static inline void pm_runtime_no_callbacks(struct device *dev) {}