linux-kernel - Re: [linux-pm] intermittent suspend problem again

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Date:	Wed, 18 Nov 2009 23:13:14 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Ferenc Wagner <wferi@...f.hu>
Cc:	linux-pm@...ts.linux-foundation.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	yakui.zhao@...el.com, LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Len Brown <lenb@...nel.org>
Subject: Re: [linux-pm] intermittent suspend problem again

On Wednesday 18 November 2009, Ferenc Wagner wrote:
> Ferenc Wagner <wferi@...f.hu> writes:
> 
> > Since I've instrumented s2disk and the hibernation path, no freeze
> > happened during hibernating the machine.
> 
> Not until I removed the delays from hibernation_platform_enter(), which
> were put there previously to get step-by-step feedback.  Removing them
> again resulted in a freeze in short course, maybe just two hibernations
> later.  The instrumentation shows it stuck in dpm_suspend_start(PMSG_HIBERNATE).
> Does it mean that some device driver is at fault?

A driver or one of the platform hooks.

> I'll check if it always fails at the same point (although tracing into
> dpm_suspend_start isn't pure fun because of the multitude of devices it
> loops over).  Is there any way to get printk output from that phase?

Compile with CONFIG_PM_VERBOSE (it does mean exactly that).

> Side question: If I run s2disk from the init=/bin/bash prompt, the
> instrumentation in acpi_enter_sleep_state_prep in drivers/acpi/acpica/hwsleep.c
> fires before the "Snapshotting system" phase, but it does not fire if I
> hibernate from the full running desktop.  (That instrumentation was put
> there to investigate the KMS-triggered STR freeze.)  What could explain
> this?

It looks like it uses the "shutdown" method when run with init=/bin/bash, but
I don't know why exactly.

Thanks,
Rafael
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