277 lines
12 KiB
Plaintext
Executable File
277 lines
12 KiB
Plaintext
Executable File
What: /sys/devices/.../power/
|
|
Date: January 2009
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power directory contains attributes
|
|
allowing the user space to check and modify some power
|
|
management related properties of given device.
|
|
|
|
What: /sys/devices/.../power/wakeup
|
|
Date: January 2009
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/wakeup attribute allows the user
|
|
space to check if the device is enabled to wake up the system
|
|
from sleep states, such as the memory sleep state (suspend to
|
|
RAM) and hibernation (suspend to disk), and to enable or disable
|
|
it to do that as desired.
|
|
|
|
Some devices support "wakeup" events, which are hardware signals
|
|
used to activate the system from a sleep state. Such devices
|
|
have one of the following two values for the sysfs power/wakeup
|
|
file:
|
|
|
|
+ "enabled\n" to issue the events;
|
|
+ "disabled\n" not to do so;
|
|
|
|
In that cases the user space can change the setting represented
|
|
by the contents of this file by writing either "enabled", or
|
|
"disabled" to it.
|
|
|
|
For the devices that are not capable of generating system wakeup
|
|
events this file is not present. In that case the device cannot
|
|
be enabled to wake up the system from sleep states.
|
|
|
|
What: /sys/devices/.../power/control
|
|
Date: January 2009
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/control attribute allows the user
|
|
space to control the run-time power management of the device.
|
|
|
|
All devices have one of the following two values for the
|
|
power/control file:
|
|
|
|
+ "auto\n" to allow the device to be power managed at run time;
|
|
+ "on\n" to prevent the device from being power managed;
|
|
|
|
The default for all devices is "auto", which means that they may
|
|
be subject to automatic power management, depending on their
|
|
drivers. Changing this attribute to "on" prevents the driver
|
|
from power managing the device at run time. Doing that while
|
|
the device is suspended causes it to be woken up.
|
|
|
|
What: /sys/devices/.../power/async
|
|
Date: January 2009
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../async attribute allows the user space to
|
|
enable or diasble the device's suspend and resume callbacks to
|
|
be executed asynchronously (ie. in separate threads, in parallel
|
|
with the main suspend/resume thread) during system-wide power
|
|
transitions (eg. suspend to RAM, hibernation).
|
|
|
|
All devices have one of the following two values for the
|
|
power/async file:
|
|
|
|
+ "enabled\n" to permit the asynchronous suspend/resume;
|
|
+ "disabled\n" to forbid it;
|
|
|
|
The value of this attribute may be changed by writing either
|
|
"enabled", or "disabled" to it.
|
|
|
|
It generally is unsafe to permit the asynchronous suspend/resume
|
|
of a device unless it is certain that all of the PM dependencies
|
|
of the device are known to the PM core. However, for some
|
|
devices this attribute is set to "enabled" by bus type code or
|
|
device drivers and in that cases it should be safe to leave the
|
|
default value.
|
|
|
|
What: /sys/devices/.../power/wakeup_count
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_count attribute contains the number
|
|
of signaled wakeup events associated with the device. This
|
|
attribute is read-only. If the device is not capable to wake up
|
|
the system from sleep states, this attribute is not present.
|
|
If the device is not enabled to wake up the system from sleep
|
|
states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_active_count
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_active_count attribute contains the
|
|
number of times the processing of wakeup events associated with
|
|
the device was completed (at the kernel level). This attribute
|
|
is read-only. If the device is not capable to wake up the
|
|
system from sleep states, this attribute is not present. If
|
|
the device is not enabled to wake up the system from sleep
|
|
states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_abort_count
|
|
Date: February 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_abort_count attribute contains the
|
|
number of times the processing of a wakeup event associated with
|
|
the device might have aborted system transition into a sleep
|
|
state in progress. This attribute is read-only. If the device
|
|
is not capable to wake up the system from sleep states, this
|
|
attribute is not present. If the device is not enabled to wake
|
|
up the system from sleep states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_expire_count
|
|
Date: February 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_expire_count attribute contains the
|
|
number of times a wakeup event associated with the device has
|
|
been reported with a timeout that expired. This attribute is
|
|
read-only. If the device is not capable to wake up the system
|
|
from sleep states, this attribute is not present. If the
|
|
device is not enabled to wake up the system from sleep states,
|
|
this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_active
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_active attribute contains either 1,
|
|
or 0, depending on whether or not a wakeup event associated with
|
|
the device is being processed (1). This attribute is read-only.
|
|
If the device is not capable to wake up the system from sleep
|
|
states, this attribute is not present. If the device is not
|
|
enabled to wake up the system from sleep states, this attribute
|
|
is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_total_time_ms
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_total_time_ms attribute contains
|
|
the total time of processing wakeup events associated with the
|
|
device, in milliseconds. This attribute is read-only. If the
|
|
device is not capable to wake up the system from sleep states,
|
|
this attribute is not present. If the device is not enabled to
|
|
wake up the system from sleep states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_max_time_ms
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_max_time_ms attribute contains
|
|
the maximum time of processing a single wakeup event associated
|
|
with the device, in milliseconds. This attribute is read-only.
|
|
If the device is not capable to wake up the system from sleep
|
|
states, this attribute is not present. If the device is not
|
|
enabled to wake up the system from sleep states, this attribute
|
|
is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_last_time_ms
|
|
Date: September 2010
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_last_time_ms attribute contains
|
|
the value of the monotonic clock corresponding to the time of
|
|
signaling the last wakeup event associated with the device, in
|
|
milliseconds. This attribute is read-only. If the device is
|
|
not enabled to wake up the system from sleep states, this
|
|
attribute is not present. If the device is not enabled to wake
|
|
up the system from sleep states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/wakeup_prevent_sleep_time_ms
|
|
Date: February 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../wakeup_prevent_sleep_time_ms attribute
|
|
contains the total time the device has been preventing
|
|
opportunistic transitions to sleep states from occurring.
|
|
This attribute is read-only. If the device is not capable to
|
|
wake up the system from sleep states, this attribute is not
|
|
present. If the device is not enabled to wake up the system
|
|
from sleep states, this attribute is empty.
|
|
|
|
What: /sys/devices/.../power/autosuspend_delay_ms
|
|
Date: September 2010
|
|
Contact: Alan Stern <stern@rowland.harvard.edu>
|
|
Description:
|
|
The /sys/devices/.../power/autosuspend_delay_ms attribute
|
|
contains the autosuspend delay value (in milliseconds). Some
|
|
drivers do not want their device to suspend as soon as it
|
|
becomes idle at run time; they want the device to remain
|
|
inactive for a certain minimum period of time first. That
|
|
period is called the autosuspend delay. Negative values will
|
|
prevent the device from being suspended at run time (similar
|
|
to writing "on" to the power/control attribute). Values >=
|
|
1000 will cause the autosuspend timer expiration to be rounded
|
|
up to the nearest second.
|
|
|
|
Not all drivers support this attribute. If it isn't supported,
|
|
attempts to read or write it will yield I/O errors.
|
|
|
|
What: /sys/devices/.../power/pm_qos_resume_latency_us
|
|
Date: March 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/pm_qos_resume_latency_us attribute
|
|
contains the PM QoS resume latency limit for the given device,
|
|
which is the maximum allowed time it can take to resume the
|
|
device, after it has been suspended at run time, from a resume
|
|
request to the moment the device will be ready to process I/O,
|
|
in microseconds. If it is equal to 0, however, this means that
|
|
the PM QoS resume latency may be arbitrary.
|
|
|
|
Not all drivers support this attribute. If it isn't supported,
|
|
it is not present.
|
|
|
|
This attribute has no effect on system-wide suspend/resume and
|
|
hibernation.
|
|
|
|
What: /sys/devices/.../power/pm_qos_latency_tolerance_us
|
|
Date: January 2014
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute
|
|
contains the PM QoS active state latency tolerance limit for the
|
|
given device in microseconds. That is the maximum memory access
|
|
latency the device can suffer without any visible adverse
|
|
effects on user space functionality. If that value is the
|
|
string "any", the latency does not matter to user space at all,
|
|
but hardware should not be allowed to set the latency tolerance
|
|
for the device automatically.
|
|
|
|
Reading "auto" from this file means that the maximum memory
|
|
access latency for the device may be determined automatically
|
|
by the hardware as needed. Writing "auto" to it allows the
|
|
hardware to be switched to this mode if there are no other
|
|
latency tolerance requirements from the kernel side.
|
|
|
|
This attribute is only present if the feature controlled by it
|
|
is supported by the hardware.
|
|
|
|
This attribute has no effect on runtime suspend and resume of
|
|
devices and on system-wide suspend/resume and hibernation.
|
|
|
|
What: /sys/devices/.../power/pm_qos_no_power_off
|
|
Date: September 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/pm_qos_no_power_off attribute
|
|
is used for manipulating the PM QoS "no power off" flag. If
|
|
set, this flag indicates to the kernel that power should not
|
|
be removed entirely from the device.
|
|
|
|
Not all drivers support this attribute. If it isn't supported,
|
|
it is not present.
|
|
|
|
This attribute has no effect on system-wide suspend/resume and
|
|
hibernation.
|
|
|
|
What: /sys/devices/.../power/pm_qos_remote_wakeup
|
|
Date: September 2012
|
|
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
|
|
Description:
|
|
The /sys/devices/.../power/pm_qos_remote_wakeup attribute
|
|
is used for manipulating the PM QoS "remote wakeup required"
|
|
flag. If set, this flag indicates to the kernel that the
|
|
device is a source of user events that have to be signaled from
|
|
its low-power states.
|
|
|
|
Not all drivers support this attribute. If it isn't supported,
|
|
it is not present.
|
|
|
|
This attribute has no effect on system-wide suspend/resume and
|
|
hibernation.
|