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

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Sudeep,

On Tue, Feb 21, 2017 at 12:14 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
> On 21/02/17 11:07, Pavel Machek 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.
>>
>> If system supports "shallow" suspend, why does not PSCI implement it?
>
> Yes it can, and IIUC it already does on this platform with CPU_SUSPEND.
> All it now needs is just to use existing "freeze" suspend mode in Linux.

How can Linux know if using "deep" suspend will allow to wake-up the system
according to configured wake-up sources, or not?

Note that "it will not, ever" is an accepted answer.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds