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    SubjectRe: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power
    Hi Sudeep,

    On Thu, Feb 23, 2017 at 4:26 PM, Geert Uytterhoeven
    <geert@linux-m68k.org> wrote:
    > On Wed, Feb 22, 2017 at 3:32 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
    >> On 22/02/17 13:38, Geert Uytterhoeven wrote:
    >>> On Wed, Feb 22, 2017 at 12:03 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
    >>> 4. Patch 3/6 adds a new "shallow" state, as it allows to save more
    >>> power (the difference may be due to suboptimal cpuidle platform support on R-Car Gen3, though),
    >>
    >> Why can't you do that in s2idle mode. Please give me the difference
    >> between your shallow state and s2idle state, not just power numbers
    >> but the actual state of CPUs and the devices in the system.
    >
    > From the Linux side, there's not much difference, except that the secondary
    > CPU cores are disabled. As that is handled by PSCI, the difference may be
    > in the PSCI implementation. I will have to check that...
    >
    > On these SoCs, the individual CPU cores and the SCU/L2 are in separate
    > (nested) power areas. Perhaps these power areas are turned off when
    > disabling the CPU cores, but not when suspending them.

    BTW, I don't care much about the extra state.

    >>> E.g. on non-PSCI platforms with an Ethernet driver that supports
    >>> Wake-on-LAN, I can do:
    >>>
    >>> ethtool -s eth0 wol g
    >>> echo mem > /sys/power/state
    >>>
    >>> and be sure that the system can be woken up by sending a WoL MagicPacket.
    >>
    >> Still possible with s2idle if CPU_SUSPEND is correctly implemented by
    >> the platform.
    >
    > Sure. But not automatic, as it needs fiddling with mem_sleep.

    I do care about this, as it affects user experience.

    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

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