From: Ferenc Wagner <wferi@niif.hu>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: linux-pm@lists.linux-foundation.org,
       Jesse Barnes <jbarnes@virtuousgeek.org>,
       Andrew Morton <akpm@linux-foundation.org>, yakui.zhao@intel.com,
       LKML <linux-kernel@vger.kernel.org>,
       ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
       Len Brown <lenb@kernel.org>
Subject: Re: [linux-pm] intermittent suspend problem again
References: <87fx93pwv2.fsf@tac.ki.iif.hu> <200911141952.50030.rjw@sisk.pl>
	<87r5rwrkqs.fsf@tac.ki.iif.hu> <200911182313.14092.rjw@sisk.pl>
Date: Wed, 18 Nov 2009 23:54:05 +0100
In-Reply-To: <200911182313.14092.rjw@sisk.pl> (Rafael J. Wysocki's message of
	"Wed, 18 Nov 2009 23:13:14 +0100")
Message-ID: <87y6m3qwaa.fsf@tac.ki.iif.hu>
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"Rafael J. Wysocki" <rjw@sisk.pl> writes:

> On Wednesday 18 November 2009, Ferenc Wagner wrote:
>> Ferenc Wagner <wferi@niif.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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