Suspend To Idle Under Linux Being Worked On For Raspberry Pi

Linux developer Stefan Wahren has been working on adding support for suspend-to-idle (s2idle) to the Raspberry Pi single board computers. It's working and there are power-savings benefits, but the downside is that initially the support is just for older Raspberry Pi boards.

There's work underway for enabling the suspend-to-idle sleep state for greater power savings during inactivity. With this Raspberry Pi effort, suspend and resume for the Raspberry Pi can be handled via the debug UART.

Initially this Raspberry Pi suspend-to-idle support is focused on the Broadcom BCM2835 SoC and has been tested with the Raspberry Pi 1 Model B, Raspberry Pi 3 Model A+, and Raspberry Pi 3 Model B+. The older SoC was initially targeted for s2idle work since its less complex and has enough documentation publicly available.

With tests by Stefan, the Raspberry Pi running but with CPUs idle saw a 1.67 Watt power consumption but during s2idle dropped to a 1.33 Watt power draw. There are known issues though with not being able to power down the USB domain and DWC2 suspend handling problems.

Details for those interested via this LKML patch series.