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

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Message-ID: <87y6m3qwaa.fsf@tac.ki.iif.hu>
Date:	Wed, 18 Nov 2009 23:54:05 +0100
From:	Ferenc Wagner <wferi@...f.hu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
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

"Rafael J. Wysocki" <rjw@...k.pl> writes:

> 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).

I've been running with CONFIG_PM_VERBOSE=y for a good while, but that
didn't help getting for example the result of the following printks to
the VGA console (0x3bc is the parallel port):

@@ -445,34 +446,66 @@ int hibernation_platform_enter(void)
         * hibernation_ops->finish() before saving the image, so we should let
         * the firmware know that we're going to enter the sleep state after all
         */
+       printk ("hibernation_ops->begin()...\n");
+       outb(16, 0x3bc);
        error = hibernation_ops->begin();
+       outb(17, 0x3bc);
+       printk ("hibernation_ops->begin(): %d\n", error);
        if (error)
                goto Close;

However, my dmesg is full of lines like

agpgart-intel 0000:00:00.0: preparing freeze
pci 0000:00:00.1: preparing freeze
pci 0000:00:00.3: preparing freeze

etc., I'll check it they are the same all the time.  Anyway, the above
printk strings aren't present in dmesg after a successful resume even,
so I must be doing something wrong...  The parport pins do change, though.
Maybe explicit levels would work better?  I can't see any other
difference from the pm_dev_dbg macro producing the above lines.

>> 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 for the tip, I'll check this too.
-- 
Regards,
Feri.
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