Re: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode

From: Sudeep Holla
Date: Tue Feb 21 2017 - 05:43:06 EST

Hi Geert,

On 20/02/17 20:33, Geert Uytterhoeven wrote:
> Enable support for "shallow" suspend mode, also known as "Standby" or
> "Power-On Suspend".
> As secondary CPU cores are taken offline, "shallow" suspend mode saves
> slightly more power than "s2idle", but less than "deep" suspend mode.
> However, unlike "deep" suspend mode, "shallow" suspend mode can be used
> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is
> an optional API in PSCI v1.0.
> List the available system suspend modes:
> $ cat /sys/power/mem_sleep
> s2idle shallow [deep]
> Suspend to "shallow" mode:
> $ echo shallow > /sys/power/mem_sleep
> $ echo mem > /sys/power/state

I don't have the links to such previous attempts handy, but we have
more elegant alternative options(suspend-to-idle) and any such attempts
to hack around the PSCI will be NACKed.