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From: Pavel Machek <pavel@ucw.cz>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
	Sebastian Capella <sebastian.capella@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Russ Dill <Russ.Dill@ti.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>, Nicolas Pitre <nico@linaro.org>,
	Santosh Shilimkar <santosh.shilimkar@ti.com>,
	Will Deacon <Will.Deacon@arm.com>,
	Cyril Chemparathy <cyril@ti.com>,
	Jonathan Austin <Jonathan.Austin@arm.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>,
	Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
Date: Sat, 22 Feb 2014 23:28:19 +0100	[thread overview]
Message-ID: <20140222222819.GA20490@amd.pavel.ucw.cz> (raw)
In-Reply-To: <20140222120910.GA9012@e102568-lin.cambridge.arm.com>

Hi!

> > return from the finisher will always be interpreted as an abort rather
> > than success (because the state has to be unwound.)
> > 
> > This is the only way to get a zero return from cpu_suspend().
> 
> Yes, that's the only reason why this code is jumping to cpu_resume, since
> all it is needed is to snapshot the CPU context and by the time the
> finisher is called that's done. Wanted to say that soft reboot is not
> useful (cache flushing and resume with MMU off), but what you are saying
> is correct. We might be saving swsusp_save return value in a global
> variable and just return from the finisher, but that's horrible and
> given the amount of time it takes to snapshot the image to disk the
> cost of this soft reboot will be dwarfed by that.

I feel bad for the "global variable" trick on x86, and if you can
avoid it, please do!

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

WARNING: multiple messages have this Message-ID (diff)
From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
Date: Sat, 22 Feb 2014 23:28:19 +0100	[thread overview]
Message-ID: <20140222222819.GA20490@amd.pavel.ucw.cz> (raw)
In-Reply-To: <20140222120910.GA9012@e102568-lin.cambridge.arm.com>

Hi!

> > return from the finisher will always be interpreted as an abort rather
> > than success (because the state has to be unwound.)
> > 
> > This is the only way to get a zero return from cpu_suspend().
> 
> Yes, that's the only reason why this code is jumping to cpu_resume, since
> all it is needed is to snapshot the CPU context and by the time the
> finisher is called that's done. Wanted to say that soft reboot is not
> useful (cache flushing and resume with MMU off), but what you are saying
> is correct. We might be saving swsusp_save return value in a global
> variable and just return from the finisher, but that's horrible and
> given the amount of time it takes to snapshot the image to disk the
> cost of this soft reboot will be dwarfed by that.

I feel bad for the "global variable" trick on x86, and if you can
avoid it, please do!

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2014-02-22 22:28 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-19  1:52 [PATCH RFC v1 0/3] hibernation support on ARM Sebastian Capella
2014-02-19  1:52 ` Sebastian Capella
2014-02-19  1:52 ` [PATCH RFC v1 1/3] ARM: Add irq disabled version of soft_restart Sebastian Capella
2014-02-19  1:52   ` Sebastian Capella
2014-02-22 10:26   ` Russell King - ARM Linux
2014-02-22 10:26     ` Russell King - ARM Linux
2014-02-24 23:13     ` Sebastian Capella
2014-02-24 23:13       ` Sebastian Capella
2014-02-25  0:22       ` Sebastian Capella
2014-02-25  0:22         ` Sebastian Capella
2014-02-25  7:56       ` Russ Dill
2014-02-25  7:56         ` Russ Dill
2014-02-25  7:56         ` Russ Dill
2014-02-25 10:27         ` Thomas Gleixner
2014-02-25 10:27           ` Thomas Gleixner
2014-02-25 17:15           ` Russ Dill
2014-02-25 17:15             ` Russ Dill
2014-02-25 17:15             ` Russ Dill
2014-02-25 23:24             ` Sebastian Capella
2014-02-25 23:24               ` Sebastian Capella
2014-02-19  1:52 ` [PATCH RFC v1 2/3] Fix hibernation restore hang in freeze_processes Sebastian Capella
2014-02-19  1:52   ` Sebastian Capella
2014-02-24  7:09   ` Ming Lei
2014-02-24  7:09     ` Ming Lei
2014-02-19  1:52 ` [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Sebastian Capella
2014-02-19  1:52   ` Sebastian Capella
2014-02-19 16:12   ` Lorenzo Pieralisi
2014-02-19 16:12     ` Lorenzo Pieralisi
2014-02-19 16:12     ` Lorenzo Pieralisi
2014-02-19 19:10     ` Russ Dill
2014-02-19 19:10       ` Russ Dill
2014-02-19 19:10       ` Russ Dill
2014-02-20 10:37       ` Lorenzo Pieralisi
2014-02-20 10:37         ` Lorenzo Pieralisi
2014-02-20 10:37         ` Lorenzo Pieralisi
2014-02-19 19:33     ` Sebastian Capella
2014-02-19 19:33       ` Sebastian Capella
2014-02-20 16:27       ` Lorenzo Pieralisi
2014-02-20 16:27         ` Lorenzo Pieralisi
2014-02-20 16:27         ` Lorenzo Pieralisi
2014-02-21 18:39         ` Sebastian Capella
2014-02-21 18:39           ` Sebastian Capella
2014-02-21 23:59           ` Sebastian Capella
2014-02-21 23:59             ` Sebastian Capella
2014-02-22  4:37             ` Sebastian Capella
2014-02-22  4:37               ` Sebastian Capella
2014-02-22  6:46               ` Russ Dill
2014-02-22  6:46                 ` Russ Dill
2014-02-22  6:46                 ` Russ Dill
2014-02-22 10:22                 ` Russell King - ARM Linux
2014-02-22 10:22                   ` Russell King - ARM Linux
2014-02-22 10:22                   ` Russell King - ARM Linux
2014-02-22 10:16         ` Russell King - ARM Linux
2014-02-22 10:16           ` Russell King - ARM Linux
2014-02-22 10:16           ` Russell King - ARM Linux
2014-02-22 12:13           ` Lorenzo Pieralisi
2014-02-22 12:13             ` Lorenzo Pieralisi
2014-02-22 12:13             ` Lorenzo Pieralisi
2014-02-22 22:30           ` Pavel Machek
2014-02-22 22:30             ` Pavel Machek
2014-02-22 22:30             ` Pavel Machek
2014-02-21  1:01     ` Sebastian Capella
2014-02-21  1:01       ` Sebastian Capella
2014-02-22 10:38     ` Russell King - ARM Linux
2014-02-22 10:38       ` Russell King - ARM Linux
2014-02-22 10:38       ` Russell King - ARM Linux
2014-02-22 12:09       ` Lorenzo Pieralisi
2014-02-22 12:09         ` Lorenzo Pieralisi
2014-02-22 12:09         ` Lorenzo Pieralisi
2014-02-22 22:28         ` Pavel Machek [this message]
2014-02-22 22:28           ` Pavel Machek
2014-02-22 22:28           ` Pavel Machek
2014-02-23 19:52         ` Sebastian Capella
2014-02-23 19:52           ` Sebastian Capella
2014-02-23 19:52           ` Sebastian Capella
2014-02-23 20:02         ` Sebastian Capella
2014-02-23 20:02           ` Sebastian Capella
2014-02-23 20:02           ` Sebastian Capella
2014-02-25 11:32           ` Lorenzo Pieralisi
2014-02-25 11:32             ` Lorenzo Pieralisi
2014-02-25 11:32             ` Lorenzo Pieralisi
2014-02-25 17:55             ` Sebastian Capella
2014-02-25 17:55               ` Sebastian Capella
2014-02-26 10:24               ` Lorenzo Pieralisi
2014-02-26 10:24                 ` Lorenzo Pieralisi
2014-02-26 10:24                 ` Lorenzo Pieralisi
2014-02-26 17:50                 ` Sebastian Capella
2014-02-26 17:50                   ` Sebastian Capella
2014-02-26 19:03                   ` Lorenzo Pieralisi
2014-02-26 19:03                     ` Lorenzo Pieralisi
2014-02-26 19:03                     ` Lorenzo Pieralisi

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