linux/include/linux/pm_runtime.h

280 lines
8.3 KiB

PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-01 00:01:31 +01:00
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>
2014-05-16 02:46:50 +02:00
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>
2014-05-16 02:46:50 +02:00