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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Dave Martin <dave.martin@linaro.org>
Cc: Frank Hofmann <frank.hofmann@tomtom.com>,
	linux-pm@lists.linux-foundation.org, tuxonice-devel@tuxonice.net,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH] ARM hibernation / suspend-to-disk support code
Date: Mon, 23 May 2011 11:12:20 +0100	[thread overview]
Message-ID: <20110523101220.GH17672__45208.1027011902$1306145619$gmane$org@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20110523100132.GC2370@arm.com>

On Mon, May 23, 2011 at 11:01:32AM +0100, Dave Martin wrote:
> On Fri, May 20, 2011 at 07:05:10PM +0100, Russell King - ARM Linux wrote:
> > Out of the list you mention above, the only thing which isn't saved are the
> > FIQ registers, and that's a problem for S2RAM too, and should be done by
> > arch/arm/kernel/fiq.c hooking into the suspend paths.
> 
> The alternative view is that the driver using FIQ owns the state in the FIQ
> mode registers and is therefore responsible for saving and restoring it
> across suspend/resume.  If so, then any additional globally implemented
> state save/restore of the FIQ mode state is unnecessary.

This seems to be most sensible - if the FIQ is being used as a software-DMA,
then the hardware side of that needs to be cleanly shutdown (eg, waiting for
the DMA to complete before proceeding) to ensure no loss of data.  That
can't happen from within the FIQ code.

I also wonder about issues of secure/non-secure stuff here too - what
that means is that if we have a driver using FIQ mode, then we have
FIQ state to save, but if not there's probably no point (or even any
way) to save that state ourselves anyway.

  reply	other threads:[~2011-05-23 10:12 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <3DCE2F529B282E4B8F53D4D8AA406A07014FFE@008-AM1MPN1-022.mgdnok.nokia.com>
2011-05-19 17:31 ` [RFC PATCH] ARM hibernation / suspend-to-disk support code Frank Hofmann
2011-05-20 11:37   ` Dave Martin
2011-05-20 11:37   ` Dave Martin
2011-05-20 12:39     ` Frank Hofmann
2011-05-20 12:39       ` Frank Hofmann
2011-05-20 15:03       ` Dave Martin
2011-05-20 15:03       ` Dave Martin
2011-05-20 16:24         ` Frank Hofmann
2011-05-23  9:42           ` Dave Martin
2011-05-23  9:42           ` Dave Martin
2011-05-20 16:24         ` Frank Hofmann
2011-05-20 17:53         ` Nicolas Pitre
2011-05-20 17:53         ` Nicolas Pitre
2011-05-20 18:07       ` Russell King - ARM Linux
2011-05-20 18:07       ` Russell King - ARM Linux
2011-05-22  6:39         ` Frank Hofmann
2011-05-20 22:27       ` [linux-pm] " Rafael J. Wysocki
2011-05-22  7:01         ` Frank Hofmann
2011-05-22  9:54           ` Rafael J. Wysocki
2011-05-22  9:54           ` Rafael J. Wysocki
2011-05-22  7:01         ` Frank Hofmann
2011-05-23  9:52         ` Dave Martin
2011-05-23  9:52         ` [linux-pm] " Dave Martin
2011-05-23 13:37           ` Frank Hofmann
2011-05-23 14:32             ` Russell King - ARM Linux
2011-05-23 14:32               ` [linux-pm] " Russell King - ARM Linux
2011-05-23 15:57               ` [RFC PATCH v2] " Frank Hofmann
2011-05-23 15:57               ` Frank Hofmann
2011-05-23 13:37           ` [RFC PATCH] " Frank Hofmann
2011-05-20 22:27       ` Rafael J. Wysocki
2011-05-20 18:05     ` Russell King - ARM Linux
2011-05-20 18:05     ` Russell King - ARM Linux
2011-05-23 10:01       ` Dave Martin
2011-05-23 10:12         ` Russell King - ARM Linux [this message]
2011-05-23 10:12         ` Russell King - ARM Linux
2011-05-23 11:16           ` Dave Martin
2011-05-23 16:11             ` Russell King - ARM Linux
2011-05-23 16:38               ` Dave Martin
2011-05-24 12:33                 ` Frank Hofmann
2011-05-24 12:33                 ` Frank Hofmann
2011-05-23 16:38               ` Dave Martin
2011-05-23 16:11             ` Russell King - ARM Linux
2011-05-23 11:16           ` Dave Martin
2011-05-23 10:01       ` Dave Martin
2011-05-24 13:27     ` [RFC] ARM hibernation, cpu-type-specific code Frank Hofmann
2011-05-19 17:31 ` [RFC PATCH] ARM hibernation / suspend-to-disk support code Frank Hofmann

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