[coreboot] ACPI S3 and S0ix (S0i3)

[Paul Menzel]

Dear coreboot folks,


Recently in Linux and coreboot, support for the “S0ix states” [1] is
introduced.

> S0ix-states represent the residency in the Intel® SoC idle standby
> power states. The S0ix states shut off part of the SoC when they are
> not in use. The S0ix states are triggered when specific conditions
> within the SoC have been achieved, for example: certain components
> are in low power states. The SoC consumes the least amount of power
> in the deepest (for example, S0i3) state.
> 
> On Linux*, Android*, and Chrome* OS, ACPI-SState represent the
> system’s residency in the ACPI Suspend-To-RAM (S3). In the Suspend-
> To-RAM state, the Linux kernel powers down many of the systems’
> components while maintaining the system’s state in its main memory.
> The system consumes the least amount of power possible while in the
> Suspend-To-RAM state. Note that any wakelock will prevent the system
> from entering the Suspend-To-RAM state.

Microsoft Windows calls this *Connected Standby* [2], and I think
supports this since 2013 or 2014.

If I understand it correctly, the motivation is to decrease time to
“wake-up”, and also to keep the device always connected to the network.
As some devices still draw a little power compared to ACPI S3, the
power usage during S0i3 is a little higher.

Is at least the first item needed with coreboot? The Google Veyron_jaq
Chromebook (Medion AKOYA S2013) I have, is done resuming as soon the
lid if fully opened. Depending on the WLAN, I believe it’s also
reconnected quite fast.

Is Chrome OS going to use the new S0i3 over S3 in the future?


Thanks,

Paul


[1] https://software.intel.com/en-us/node/544551
[2] https://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/f46fc046-91bf-4d7c-bfb4-55e7554e3b98/clarification-on-system-states?forum=wdk
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