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Fake Suspend

Overview

Fake suspend is available on platforms that do not support hardware suspend and resume - SM8550, S922X and H700. This allows the device to enter a short term low power state, with a configurable shutdown delay.

Fake suspend can be activated by pressing the power button or closing the lid on clamshell devices. The following configurable actions are performed:

  • display or backlight is turned off
  • audio is muted
  • CPU / GPU governors are set to powersave
  • CPU cores 1...n are brought offline, core 0 left online
  • controls are disabled (besides lid / power button)
  • a shutdown delay timer begins

If a game is running when fake suspend is triggered, it will continue to run in a low power state, allowing quick gameplay resume.

When the power button is pressed again, or the lid is opened on clamshell devices, the following actions are performed as required:

  • display or backlight is turned on
  • audio is unmuted
  • CPU / GPU governors are restored to their pre-suspend value
  • CPU cores 1...n are brought back online
  • controls are enabled
  • the shutdown delay timer is cancelled

If the shutdown delay timer expires before resume is triggered, the device will shut down.

Configuration

Behaviour can be configured in the EmulationStation 'System Settings' menu, 'Suspend' section menu.

Shutdown Delay

This setting controls how long fake suspend is active (0 - 30 minutes: default 0 minutes) before a timed shutdown occurs, when not in-game. If the delay is set to 0 minutes, shutdown will occur immediately.

Shutdown delay (in game)

This setting controls how long fake suspend is active (0 - 30 minutes: default 15 minutes) before a timed shutdown occurs, when in-game. If the delay is set to 0 minutes, shutdown will occur immediately.

Enable core parking

This setting controls whether or not CPU cores 1...n are brought offline during fake suspend. Process affinity settings are lost when cores are brought offline, so disable this if you depend on core pinning, for example pinning an emulator to little cores to save battery, or to big cores for better performance.

Enable DPMS

This setting controls whether the display is turned off using window manager DPMS or using simple backlight control. If you encounter instability issues with DPMS, eg hard reboots on resume, disable this setting.

Charging

If a charger connection is detected, the suspend actions are triggered, but no shutdown will be performed.

This is intended to enable charging while in a low-power state - connect a charger, then tap power or close the lid.

Most of the supported devices will boot up again when shut down with a charger connected, but this time not in a low power state which defeats the purpose of fake suspend.

HDMI

If you have a HDMI cable connected, the suspend actions and shutdown delay are not triggered.

This is intended to enable 'docking' clamshell devices with the lid closed.

Video out via USB-C DP Alt Mode is not currently detected, only HDMI.