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This patch (as1427) implements the "autosuspend" facility for runtime PM. A few new fields are added to the dev_pm_info structure and several new PM helper functions are defined, for telling the PM core whether or not a device uses autosuspend, for setting the autosuspend delay, and for marking periods of device activity. Drivers that do not want to use autosuspend can continue using the same helper functions as before; their behavior will not change. In addition, drivers supporting autosuspend can also call the old helper functions to get the old behavior. The details are all explained in Documentation/power/runtime_pm.txt and Documentation/ABI/testing/sysfs-devices-power. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
168 lines
6.8 KiB
Plaintext
168 lines
6.8 KiB
Plaintext
What: /sys/devices/.../power/
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Date: January 2009
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../power directory contains attributes
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allowing the user space to check and modify some power
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management related properties of given device.
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What: /sys/devices/.../power/wakeup
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Date: January 2009
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../power/wakeup attribute allows the user
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space to check if the device is enabled to wake up the system
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from sleep states, such as the memory sleep state (suspend to
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RAM) and hibernation (suspend to disk), and to enable or disable
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it to do that as desired.
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Some devices support "wakeup" events, which are hardware signals
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used to activate the system from a sleep state. Such devices
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have one of the following two values for the sysfs power/wakeup
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file:
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+ "enabled\n" to issue the events;
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+ "disabled\n" not to do so;
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In that cases the user space can change the setting represented
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by the contents of this file by writing either "enabled", or
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"disabled" to it.
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For the devices that are not capable of generating system wakeup
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events this file contains "\n". In that cases the user space
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cannot modify the contents of this file and the device cannot be
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enabled to wake up the system.
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What: /sys/devices/.../power/control
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Date: January 2009
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../power/control attribute allows the user
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space to control the run-time power management of the device.
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All devices have one of the following two values for the
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power/control file:
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+ "auto\n" to allow the device to be power managed at run time;
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+ "on\n" to prevent the device from being power managed;
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The default for all devices is "auto", which means that they may
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be subject to automatic power management, depending on their
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drivers. Changing this attribute to "on" prevents the driver
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from power managing the device at run time. Doing that while
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the device is suspended causes it to be woken up.
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What: /sys/devices/.../power/async
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Date: January 2009
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../async attribute allows the user space to
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enable or diasble the device's suspend and resume callbacks to
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be executed asynchronously (ie. in separate threads, in parallel
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with the main suspend/resume thread) during system-wide power
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transitions (eg. suspend to RAM, hibernation).
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All devices have one of the following two values for the
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power/async file:
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+ "enabled\n" to permit the asynchronous suspend/resume;
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+ "disabled\n" to forbid it;
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The value of this attribute may be changed by writing either
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"enabled", or "disabled" to it.
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It generally is unsafe to permit the asynchronous suspend/resume
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of a device unless it is certain that all of the PM dependencies
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of the device are known to the PM core. However, for some
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devices this attribute is set to "enabled" by bus type code or
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device drivers and in that cases it should be safe to leave the
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default value.
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What: /sys/devices/.../power/wakeup_count
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_count attribute contains the number
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of signaled wakeup events associated with the device. This
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attribute is read-only. If the device is not enabled to wake up
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the system from sleep states, this attribute is empty.
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What: /sys/devices/.../power/wakeup_active_count
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_active_count attribute contains the
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number of times the processing of wakeup events associated with
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the device was completed (at the kernel level). This attribute
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is read-only. If the device is not enabled to wake up the
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system from sleep states, this attribute is empty.
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What: /sys/devices/.../power/wakeup_hit_count
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_hit_count attribute contains the
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number of times the processing of a wakeup event associated with
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the device might prevent the system from entering a sleep state.
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This attribute is read-only. If the device is not enabled to
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wake up the system from sleep states, this attribute is empty.
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What: /sys/devices/.../power/wakeup_active
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_active attribute contains either 1,
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or 0, depending on whether or not a wakeup event associated with
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the device is being processed (1). This attribute is read-only.
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If the device is not enabled to wake up the system from sleep
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states, this attribute is empty.
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What: /sys/devices/.../power/wakeup_total_time_ms
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_total_time_ms attribute contains
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the total time of processing wakeup events associated with the
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device, in milliseconds. This attribute is read-only. If the
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device is not enabled to wake up the system from sleep states,
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this attribute is empty.
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What: /sys/devices/.../power/wakeup_max_time_ms
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_max_time_ms attribute contains
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the maximum time of processing a single wakeup event associated
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with the device, in milliseconds. This attribute is read-only.
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If the device is not enabled to wake up the system from sleep
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states, this attribute is empty.
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What: /sys/devices/.../power/wakeup_last_time_ms
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Date: September 2010
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Contact: Rafael J. Wysocki <rjw@sisk.pl>
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Description:
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The /sys/devices/.../wakeup_last_time_ms attribute contains
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the value of the monotonic clock corresponding to the time of
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signaling the last wakeup event associated with the device, in
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milliseconds. This attribute is read-only. If the device is
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not enabled to wake up the system from sleep states, this
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attribute is empty.
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What: /sys/devices/.../power/autosuspend_delay_ms
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Date: September 2010
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Contact: Alan Stern <stern@rowland.harvard.edu>
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Description:
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The /sys/devices/.../power/autosuspend_delay_ms attribute
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contains the autosuspend delay value (in milliseconds). Some
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drivers do not want their device to suspend as soon as it
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becomes idle at run time; they want the device to remain
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inactive for a certain minimum period of time first. That
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period is called the autosuspend delay. Negative values will
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prevent the device from being suspended at run time (similar
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to writing "on" to the power/control attribute). Values >=
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1000 will cause the autosuspend timer expiration to be rounded
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up to the nearest second.
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Not all drivers support this attribute. If it isn't supported,
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attempts to read or write it will yield I/O errors.
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