In M61 and later, there are settings at chrome://settings/power for controlling the idle and lid-closed behaviors.
The Keep Awake extension can be used to quickly toggle between different idle behaviors. It uses the chrome.power API.
If the system is in dev mode, the disable_idle_suspend powerd pref can be used to instruct powerd to not suspend the system in response to inactivity. This pref is automatically set at /usr/share/power_manager/disable_idle_suspend in dev or test images. To set it manually, write 1 to /var/lib/power_manager/disable_idle_suspend. powerd will apply the updated pref immediately.
Similarly, you can keep your development system awake while its lid is closed by running the following as the root user:
# ectool forcelidopen 1 # echo 0 >/var/lib/power_manager/use_lid # restart powerd
This should persist as long as you don‘t wipe the device’s stateful partition. To undo it, run the following:
# ectool forcelidopen 0 # rm -f /var/lib/power_manager/use_lid # restart powerd
The powerd_dbus_suspend program can be run from crosh or an SSH session to exercise the normal suspend path; it sends a D-Bus message to powerd asking it to suspend the system. See also memory_suspend_test and suspend_stress_test.
The powerd_dbus_reboot program can be run from crosh or an SSH session to exercise the normal reboot path; it sends a D-Bus message to powerd asking it to reboot the system.
The powerd_dbus_shutdown program can be run from crosh or an SSH session to exercise the normal shut down path; it sends a D-Bus message to powerd asking it to shut down the system.
There are several different techniques that can be used to temporarily override the power manager's default behavior:
This utility program was added in R26 to exercise the code path that Chrome uses to override the default power management policy (which was needed for enterprise). Run it with --help to see the available fields or without any arguments to restore the default policy. Note that Chrome may override any policy that you manually set; this happens when the related Chrome preferences are changed or when Chrome is restarted, for instance.
At a high level, the powerd prefs system allows values to be read from chromeos-config or from the read-only partition at /usr/share/power_manager. Powerd has many more features, and these are explored in detail in the prefs documentation.
For testing and debugging, it an be useful to override pref values. This can be done by writing files onto the read-write partition at /var/lib/power_manager. See the example of setting the use_lid preference above, or see the prefs documentation for more detail.
set_short_powerd_timeouts script can be used to quickly set inactivity timeouts to low values and restart powerd. To disable the power manager's timeouts more permanently, run the following as root:
echo 1 >/var/lib/power_manager/ignore_external_policy for i in {,un}plugged_{dim,off,suspend}_ms; do echo 0 >/var/lib/power_manager/$i done restart powerd
The power manager gives other daemons an opportunity to do any preparation that they need to just before the system is suspended. See suspend.proto for a detailed description of the process, along with the definitions of the protocol buffers that are passed over D-Bus, and suspend_delay_sample for example usage.
This is often needed by code that updates firmware. Before powerd attempts to suspend the system or shut it down, it checks for the presence of one or more lockfiles, each containing the PID of a process that shouldn't be interrupted. If it finds one, it defers the attempt for 10 seconds before trying again.
powerd uses several hard-coded lockfile paths within /run/lock, but new lockfiles should be written to the /run/lock/power_override directory. Your process should unlink its lockfile when it exits or no longer needs to block power management.