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From: Mark Rutland <mark.rutland@arm.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>, Pavel Machek <pavel@ucw.cz>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Lina Iyer <lina.iyer@linaro.org>,
	John Stultz <john.stultz@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>, Rob Herring <robh+dt@kernel.org>,
	Magnus Damm <magnus.damm@gmail.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Linux PM list <linux-pm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode
Date: Tue, 21 Feb 2017 17:20:13 +0000	[thread overview]
Message-ID: <20170221172012.GD8605@leverpostej> (raw)
In-Reply-To: <CAMuHMdVmu4AYZ6MZHd79N2-2gELR6s3oZ46UnEszCfLvHymY1w@mail.gmail.com>

Hi,

On Tue, Feb 21, 2017 at 05:32:50PM +0100, Geert Uytterhoeven wrote:
> 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?

My understanding is that if a device can wake the system from
PSCI_SYSTEM_SUSPEND, it should be described in the DT as a wakeup source
[1]. So we should be able to determine the set of devices which can wake
the system from a suspend. We shouldn't assume that other devices can
(though I don't precisely what we do currently).

Otherwise, where PSCI_CPU_SUSPEND, we'd expect that most devices
(barring cpu-local timers) can wake up CPUs, and hence the system, by
raising an interrupt.

Thanks,
Mark.

[1] Documentation/devicetree/bindings/power/wakeup-source.txt

  reply	other threads:[~2017-02-21 17:20 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-20 20:33 [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 1/6] alarmtimer: Postpone wake-up source registration until really available Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 2/6] PM / Wakeup: Add wakeup_source_available() Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Geert Uytterhoeven
2017-02-21 10:42   ` Sudeep Holla
2017-02-21 16:23     ` Geert Uytterhoeven
2017-02-21 16:51       ` Sudeep Holla
2017-02-21 11:07   ` Pavel Machek
2017-02-21 11:14     ` Sudeep Holla
2017-02-21 16:32       ` Geert Uytterhoeven
2017-02-21 17:20         ` Mark Rutland [this message]
2017-02-21 18:06           ` Geert Uytterhoeven
2017-02-21 18:18             ` Mark Rutland
2017-02-21 18:23               ` Geert Uytterhoeven
2017-02-21 17:22         ` Sudeep Holla
2017-02-22 13:47           ` Geert Uytterhoeven
2017-02-22 14:35             ` Sudeep Holla
2017-02-20 20:33 ` [PATCH/RFC 4/6] drivers: firmware: psci: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Geert Uytterhoeven
2017-02-21 10:50   ` Sudeep Holla
2017-02-21 16:36     ` Geert Uytterhoeven
2017-02-21 16:49       ` Sudeep Holla
2017-02-21 11:07   ` Pavel Machek
2017-02-21 16:36     ` Geert Uytterhoeven
2017-02-21 17:54     ` Mark Rutland
2017-02-21 17:48   ` Mark Rutland
2017-02-22 14:05     ` Geert Uytterhoeven
2017-02-22 14:57       ` Rafael J. Wysocki
2017-02-20 20:33 ` [PATCH/RFC 5/6] arm64: dts: r8a7795: Fix non-PMIC wake-up sources Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 6/6] arm64: dts: r8a7796: " Geert Uytterhoeven
2017-02-21 10:38 ` [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Sudeep Holla
2017-02-21 16:21   ` Geert Uytterhoeven
2017-02-21 16:45     ` Sudeep Holla
2017-02-21 17:34       ` Geert Uytterhoeven
2017-02-21 17:51         ` Sudeep Holla
2017-02-21 18:27           ` Sudeep Holla
2017-02-21 18:45             ` Sudeep Holla
2017-02-22  1:14               ` Rafael J. Wysocki
2017-02-22 11:03                 ` Sudeep Holla
2017-02-22 13:38                   ` Geert Uytterhoeven
2017-02-22 14:32                     ` Sudeep Holla
2017-02-22 14:50                       ` Rafael J. Wysocki
2017-02-22 15:24                         ` Sudeep Holla
2017-02-23 15:26                       ` Geert Uytterhoeven
2017-02-23 15:34                         ` Geert Uytterhoeven
2017-02-23 15:58                           ` Sudeep Holla
2017-02-23 15:53                         ` Sudeep Holla
2017-02-22 13:14                 ` Geert Uytterhoeven
2017-02-22 14:31                   ` Rafael J. Wysocki

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