linux-kernel - Re: [RFC][PATCH 0/3] PM: Asynchronous suspend and resume

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Date:	Fri, 14 Aug 2009 23:31:26 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	"linux-pm" <linux-pm@...ts.linux-foundation.org>,
	"linux-acpi" <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Zhang Rui <rui.zhang@...el.com>, Len Brown <lenb@...nel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: [RFC][PATCH 0/3] PM: Asynchronous suspend and resume

On Friday 14 August 2009, Alan Stern wrote:
> On Fri, 14 Aug 2009, Rafael J. Wysocki wrote:
> 
> > On Friday 14 August 2009, Alan Stern wrote:
> > > On Thu, 13 Aug 2009, Rafael J. Wysocki wrote:
> > > 
> > > > > No, I've only tested it with a few selected drivers.  I'm going to try the
> > > > > "async everyone" scenario, though.
> > > > 
> > > > On HP nx6325 booted with init=/bin/bash it doesn't pass the
> > > > 'echo devices > /sys/power/pm_test && echo mem > /sys/power/state' test.
> > > > 
> > > > The suspend part actually seems to work, but the resume part crashes
> > > > miserably.
> > > 
> > > Any details?  Can you tell where it crashes?
> > 
> > Unfortunately it ends up in a continuous flood of backtraces, so I can't
> > say much.
> 
> Same sort of thing happened with me, but it appeared to happen during 
> suspend.  (I say "appeared" because the system froze for a while at the 
> start of the suspend until I hit a key.  This may be related to all the 
> recent churn in the TTY layer, combined with the fact that I was using 
> a serial console.  It didn't help -- none of the backtraces got sent 
> out the serial port.)
> 
> > However, if I set async_suspend for all PCI devices, as well as for ACPI battery
> > and i8042, everything apparently works, even with real suspend-resume.
> 
> I think it would be worthwhile to track down these unknown problems and 
> dependencies.  It won't be easy, though...

Agreed.

Hm.  Perhaps it's a good idea to get this code in, so that people can play
with it.  The more people will look into this, the greater the chance to
identify problematic drivers.

Rafael
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