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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Sudeep Holla <sudeep.holla@arm.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Lina Iyer <lina.iyer@linaro.org>,
	John Stultz <john.stultz@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
	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 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power
Date: Wed, 22 Feb 2017 02:14:54 +0100	[thread overview]
Message-ID: <1975396.x0czmkNPOW@aspire.rjw.lan> (raw)
In-Reply-To: <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com>

On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote:
> 
> On 21/02/17 18:27, Sudeep Holla wrote:
> > 
> > 
> > On 21/02/17 17:51, Sudeep Holla wrote:
> >>
> >>
> >> On 21/02/17 17:34, Geert Uytterhoeven wrote:
> > 
> > [...]
> > 
> >>>
> >>> The SoC can wake-up. It's just not guaranteed that it can wake-up using
> >>> the wakeup-source configured from Linux. Which wakeup-sources are available
> >>> depends on the actual PSCI implementation.  It's not specified by the PSCI
> >>> specification.
> >>>
> >>>> Just botching whatever shallow state you can enter on a particular SoC
> >>>> into standard "mem" state sounds *horrible* to me.
> >>>
> >>> That's more or less what /sys/power/mem_sleep does, though.
> >>>
> >>
> >> OK, I will go through that in detail.
> >>
> > 
> > OK, I went through the patch and the main intention is was added.
> > So I will begin by summarizing my understanding:
> > 
> > A new suspend interface(/sys/power/mem_sleep) is added to allow the
> > "mem" string in /sys/power/state to represent multiple things that can
> > be selected.
> > 
> > Before:
> > A. echo freeze > /sys/power/state ---> Enters s2idle
> > B. echo mem > /sys/power/state ---> Enters s2r(a.k.a now deep mem sleep)
> > 
> > After:
> > 1. echo freeze > /sys/power/state ---> Enters s2idle still same
> > 2. echo s2idle > /sys/power/mem_sleep
> >    echo mem > /sys/power/state ---> Also enter s2idle
> > 3. echo deep > /sys/power/mem_sleep
> >    echo mem > /sys/power/state ---> Also enter s2r(same as [B] above)
> > 
> > Please note I have carefully dropped standby/shallow as we will not
> > support that state on ARM64 platforms(refer previous discussions for the
> > same)
> > 
> > Now IIUC, you need 2 above. So, since this new interface allow mem to
> > mean "s2idle", we need to fix the core to register default suspend_ops
> > to achieve what you need. 
> 
> I take this back, you have everything you need in place, nothing needs
> to be done. I just checked again. If I don't register PSCI suspend_ops,
> I still get mem in /sys/power/state with s2idle in /sys/power/mem_sleep
> which is exactly what we need. Again we don't support standby/shallow
> state on ARM64/PSCI.

Except for one thing which may or may not be a concern here.

Suspend to idle should only go into states in which all of the available wakeup
devices work.  If there are devices that cannot wake you up from a given state,
this isn't "idle" any more, is it?

As for the device wakeup disable/enable interface, it is for controlling
whether or not a given device should be allowed to generate wakeup signals at
all.

The information on what states a given device can wake up the system from is
platform-specific and generally would need to be taken into consideration at
the platform level.

Thanks,
Rafael

WARNING: multiple messages have this Message-ID
From: rjw@rjwysocki.net (Rafael J. Wysocki)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power
Date: Wed, 22 Feb 2017 02:14:54 +0100	[thread overview]
Message-ID: <1975396.x0czmkNPOW@aspire.rjw.lan> (raw)
In-Reply-To: <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com>

On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote:
> 
> On 21/02/17 18:27, Sudeep Holla wrote:
> > 
> > 
> > On 21/02/17 17:51, Sudeep Holla wrote:
> >>
> >>
> >> On 21/02/17 17:34, Geert Uytterhoeven wrote:
> > 
> > [...]
> > 
> >>>
> >>> The SoC can wake-up. It's just not guaranteed that it can wake-up using
> >>> the wakeup-source configured from Linux. Which wakeup-sources are available
> >>> depends on the actual PSCI implementation.  It's not specified by the PSCI
> >>> specification.
> >>>
> >>>> Just botching whatever shallow state you can enter on a particular SoC
> >>>> into standard "mem" state sounds *horrible* to me.
> >>>
> >>> That's more or less what /sys/power/mem_sleep does, though.
> >>>
> >>
> >> OK, I will go through that in detail.
> >>
> > 
> > OK, I went through the patch and the main intention is was added.
> > So I will begin by summarizing my understanding:
> > 
> > A new suspend interface(/sys/power/mem_sleep) is added to allow the
> > "mem" string in /sys/power/state to represent multiple things that can
> > be selected.
> > 
> > Before:
> > A. echo freeze > /sys/power/state ---> Enters s2idle
> > B. echo mem > /sys/power/state ---> Enters s2r(a.k.a now deep mem sleep)
> > 
> > After:
> > 1. echo freeze > /sys/power/state ---> Enters s2idle still same
> > 2. echo s2idle > /sys/power/mem_sleep
> >    echo mem > /sys/power/state ---> Also enter s2idle
> > 3. echo deep > /sys/power/mem_sleep
> >    echo mem > /sys/power/state ---> Also enter s2r(same as [B] above)
> > 
> > Please note I have carefully dropped standby/shallow as we will not
> > support that state on ARM64 platforms(refer previous discussions for the
> > same)
> > 
> > Now IIUC, you need 2 above. So, since this new interface allow mem to
> > mean "s2idle", we need to fix the core to register default suspend_ops
> > to achieve what you need. 
> 
> I take this back, you have everything you need in place, nothing needs
> to be done. I just checked again. If I don't register PSCI suspend_ops,
> I still get mem in /sys/power/state with s2idle in /sys/power/mem_sleep
> which is exactly what we need. Again we don't support standby/shallow
> state on ARM64/PSCI.

Except for one thing which may or may not be a concern here.

Suspend to idle should only go into states in which all of the available wakeup
devices work.  If there are devices that cannot wake you up from a given state,
this isn't "idle" any more, is it?

As for the device wakeup disable/enable interface, it is for controlling
whether or not a given device should be allowed to generate wakeup signals at
all.

The information on what states a given device can wake up the system from is
platform-specific and generally would need to be taken into consideration at
the platform level.

Thanks,
Rafael

  reply	other threads:[~2017-02-22  1:20 UTC|newest]

Thread overview: 145+ 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 ` 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   ` Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 2/6] PM / Wakeup: Add wakeup_source_available() Geert Uytterhoeven
2017-02-20 20:33   ` Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode Geert Uytterhoeven
2017-02-20 20:33   ` Geert Uytterhoeven
2017-02-21 10:42   ` Sudeep Holla
2017-02-21 10:42     ` Sudeep Holla
2017-02-21 16:23     ` Geert Uytterhoeven
2017-02-21 16:23       ` Geert Uytterhoeven
2017-02-21 16:23       ` Geert Uytterhoeven
2017-02-21 16:51       ` Sudeep Holla
2017-02-21 16:51         ` Sudeep Holla
2017-02-21 16:51         ` Sudeep Holla
2017-02-21 11:07   ` Pavel Machek
2017-02-21 11:07     ` Pavel Machek
2017-02-21 11:07     ` Pavel Machek
2017-02-21 11:14     ` Sudeep Holla
2017-02-21 11:14       ` Sudeep Holla
2017-02-21 11:14       ` Sudeep Holla
2017-02-21 16:32       ` Geert Uytterhoeven
2017-02-21 16:32         ` Geert Uytterhoeven
2017-02-21 16:32         ` Geert Uytterhoeven
2017-02-21 17:20         ` Mark Rutland
2017-02-21 17:20           ` Mark Rutland
2017-02-21 17:20           ` Mark Rutland
2017-02-21 17:20           ` Mark Rutland
2017-02-21 18:06           ` Geert Uytterhoeven
2017-02-21 18:06             ` Geert Uytterhoeven
2017-02-21 18:06             ` Geert Uytterhoeven
2017-02-21 18:06             ` Geert Uytterhoeven
2017-02-21 18:18             ` Mark Rutland
2017-02-21 18:18               ` Mark Rutland
2017-02-21 18:18               ` Mark Rutland
2017-02-21 18:23               ` Geert Uytterhoeven
2017-02-21 18:23                 ` Geert Uytterhoeven
2017-02-21 18:23                 ` Geert Uytterhoeven
2017-02-21 18:23                 ` Geert Uytterhoeven
2017-02-21 17:22         ` Sudeep Holla
2017-02-21 17:22           ` Sudeep Holla
2017-02-21 17:22           ` Sudeep Holla
2017-02-21 17:22           ` Sudeep Holla
2017-02-22 13:47           ` Geert Uytterhoeven
2017-02-22 13:47             ` Geert Uytterhoeven
2017-02-22 13:47             ` Geert Uytterhoeven
2017-02-22 14:35             ` Sudeep Holla
2017-02-22 14:35               ` Sudeep Holla
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
2017-02-20 20:33   ` Geert Uytterhoeven
2017-02-21 10:50   ` Sudeep Holla
2017-02-21 10:50     ` Sudeep Holla
2017-02-21 16:36     ` Geert Uytterhoeven
2017-02-21 16:36       ` Geert Uytterhoeven
2017-02-21 16:36       ` Geert Uytterhoeven
2017-02-21 16:49       ` Sudeep Holla
2017-02-21 16:49         ` Sudeep Holla
2017-02-21 16:49         ` Sudeep Holla
2017-02-21 11:07   ` Pavel Machek
2017-02-21 11:07     ` Pavel Machek
2017-02-21 16:36     ` Geert Uytterhoeven
2017-02-21 16:36       ` Geert Uytterhoeven
2017-02-21 16:36       ` Geert Uytterhoeven
2017-02-21 17:54     ` Mark Rutland
2017-02-21 17:54       ` Mark Rutland
2017-02-21 17:48   ` Mark Rutland
2017-02-21 17:48     ` Mark Rutland
2017-02-22 14:05     ` Geert Uytterhoeven
2017-02-22 14:05       ` Geert Uytterhoeven
2017-02-22 14:05       ` Geert Uytterhoeven
2017-02-22 14:57       ` Rafael J. Wysocki
2017-02-22 14:57         ` Rafael J. Wysocki
2017-02-22 14:57         ` Rafael J. Wysocki
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   ` Geert Uytterhoeven
2017-02-20 20:33   ` Geert Uytterhoeven
2017-02-20 20:33 ` [PATCH/RFC 6/6] arm64: dts: r8a7796: " Geert Uytterhoeven
2017-02-20 20:33   ` 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 10:38   ` Sudeep Holla
2017-02-21 16:21   ` Geert Uytterhoeven
2017-02-21 16:21     ` Geert Uytterhoeven
2017-02-21 16:21     ` Geert Uytterhoeven
2017-02-21 16:45     ` Sudeep Holla
2017-02-21 16:45       ` Sudeep Holla
2017-02-21 16:45       ` Sudeep Holla
2017-02-21 16:45       ` Sudeep Holla
2017-02-21 17:34       ` Geert Uytterhoeven
2017-02-21 17:34         ` Geert Uytterhoeven
2017-02-21 17:34         ` Geert Uytterhoeven
2017-02-21 17:51         ` Sudeep Holla
2017-02-21 17:51           ` Sudeep Holla
2017-02-21 17:51           ` Sudeep Holla
2017-02-21 18:27           ` Sudeep Holla
2017-02-21 18:27             ` Sudeep Holla
2017-02-21 18:27             ` Sudeep Holla
2017-02-21 18:27             ` Sudeep Holla
2017-02-21 18:45             ` Sudeep Holla
2017-02-21 18:45               ` Sudeep Holla
2017-02-21 18:45               ` Sudeep Holla
2017-02-21 18:45               ` Sudeep Holla
2017-02-22  1:14               ` Rafael J. Wysocki [this message]
2017-02-22  1:14                 ` Rafael J. Wysocki
2017-02-22  1:14                 ` Rafael J. Wysocki
2017-02-22 11:03                 ` Sudeep Holla
2017-02-22 11:03                   ` Sudeep Holla
2017-02-22 11:03                   ` Sudeep Holla
2017-02-22 13:38                   ` Geert Uytterhoeven
2017-02-22 13:38                     ` Geert Uytterhoeven
2017-02-22 13:38                     ` Geert Uytterhoeven
2017-02-22 14:32                     ` Sudeep Holla
2017-02-22 14:32                       ` Sudeep Holla
2017-02-22 14:32                       ` Sudeep Holla
2017-02-22 14:32                       ` Sudeep Holla
2017-02-22 14:50                       ` Rafael J. Wysocki
2017-02-22 14:50                         ` Rafael J. Wysocki
2017-02-22 14:50                         ` Rafael J. Wysocki
2017-02-22 14:50                         ` Rafael J. Wysocki
2017-02-22 15:24                         ` Sudeep Holla
2017-02-22 15:24                           ` Sudeep Holla
2017-02-22 15:24                           ` Sudeep Holla
2017-02-22 15:24                           ` Sudeep Holla
2017-02-23 15:26                       ` Geert Uytterhoeven
2017-02-23 15:26                         ` Geert Uytterhoeven
2017-02-23 15:26                         ` Geert Uytterhoeven
2017-02-23 15:34                         ` Geert Uytterhoeven
2017-02-23 15:34                           ` Geert Uytterhoeven
2017-02-23 15:34                           ` Geert Uytterhoeven
2017-02-23 15:58                           ` Sudeep Holla
2017-02-23 15:58                             ` Sudeep Holla
2017-02-23 15:58                             ` Sudeep Holla
2017-02-23 15:53                         ` Sudeep Holla
2017-02-23 15:53                           ` Sudeep Holla
2017-02-23 15:53                           ` Sudeep Holla
2017-02-23 15:53                           ` Sudeep Holla
2017-02-22 13:14                 ` Geert Uytterhoeven
2017-02-22 13:14                   ` Geert Uytterhoeven
2017-02-22 13:14                   ` Geert Uytterhoeven
2017-02-22 14:31                   ` Rafael J. Wysocki
2017-02-22 14:31                     ` Rafael J. Wysocki
2017-02-22 14:31                     ` Rafael J. Wysocki
2017-02-22 14:31                     ` Rafael J. Wysocki

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