linux-kernel - Re: Suspend/resume regressions on Lenovo S10-3

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Message-Id: <201206080830.29686.rjw@sisk.pl>
Date:	Fri, 8 Jun 2012 08:30:29 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
Cc:	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Linux PM mailing list <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Tomas M." <tmezzadra@...il.com>, Ferenc Wagner <wferi@...f.hu>,
	Arnd Bergmann <arnd@...db.de>, Len Brown <len.brown@...el.com>,
	Kevin Hilman <khilman@...com>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Jean Pihet <j-pihet@...com>,
	Trinabh Gupta <g.trinabh@...il.com>,
	linux-pm@...ts.linux-foundation.org,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	preeti@...ux.vnet.ibm.com
Subject: Re: Suspend/resume regressions on Lenovo S10-3

On Wednesday, June 06, 2012, Deepthi Dharwar wrote:
> On 06/06/2012 07:13 PM, Rafael J. Wysocki wrote:
> 
> > On Wednesday, June 06, 2012, Deepthi Dharwar wrote:
> >> On 05/28/2012 07:23 AM, Dave Hansen wrote:
> >>
> >>> I have a Lenovo S10-3 Atom netbook.  It's always had some amount of
> >>> trouble working with the intel_idle driver, so I usually compile that
> >>> out an use the acpi one.  However, just after 3.1, suspend/resume broke.
> >>>  'echo mem > /sys/power/state' would hang before suspending.  I bisected
> >>> it down to the commits around:
> >>>
> >>> 	e978aa7d7d57d04eb5f88a7507c4fb98577def77 / v3.1-1-ge978aa7
> >>>
> >>> by Deepthi.  But, current mainline (v3.4-07644-g07acfc2) hangs with a
> >>> different symptom: it suspends, but hangs on resume from suspend.  I
> >>> think _that_ delta in the behavior was caused by:
> >>>
> >>> 	3439a8da16bcad6b0982ece938c9f8299bb53584
> >>>
> >>>         ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend
> >>> 		regression)
> >>>
> >>> It's a bit of a pain to bisect these two different things in parallel.
> >>> I was trying to tell git bisect 'good' on working suspend/resume, 'bad'
> >>> on the hang during resume, and 'skip' on the hangs _during_ suspend.  83
> >>> kernels in, I'm not sure that's working very well. :)
> >>>
> >>> Deepthi, do you have any idea why your patches broke me in the first
> >>> place?  Perhaps we should fix that regression first before we go on and
> >>> try to figure out what changed to let it suspend again, but break later.
> >>
> >>
> >> Hi Dave,
> >>
> >> Sorry about my patches breaking your suspend-resume.
> >>
> >> I, basically tried out building and booting 3.1 kernel with 
> >> my patch set to reproduce the failure. I could clearly
> >> see suspend not happening. It turns out to be 
> >> a bug with my first patch in global registration
> >> series submitted earlier.
> >>
> >> e978aa7d7d57d04eb5f88a7507c4fb98577def77 / v3.1-1-ge978aa7
> >>
> >> The following patch, fixes the suspend issues
> >> seen on my laptop due to earlier cpuidle cleanup 
> >> (Lenevo T420 booting with acpi_idle enabled). 
> >> Can you please give this a try
> >> on top of my patch set (without Rafael's fix) 
> >> and see if it fixes the problem for you. 
> >> I am not reverting acpi_idle_suspend flag and 
> >> hopefully it should resume fine too. 
> >>
> >> ---
> >>
> >> This patch fixes suspend-resume issue seen in the kernel 3.1
> >> series using acpi_idle_driver because of cpuidle global 
> >> registration cleanup.
> >> Here, when acpi_idle_suspend flag was set ( during suspend)
> >> the interrupts were not getting enabled in acpi_idle_enter_bm()
> >> routine which was causing the system to hang.
> >>
> >>
> >> Signed-off-by: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
> >>
> >> ---
> >>  drivers/acpi/processor_idle.c |    3 ++-
> >>  1 files changed, 2 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> >> index 24fe3af..6e35293 100644
> >> --- a/drivers/acpi/processor_idle.c
> >> +++ b/drivers/acpi/processor_idle.c
> >> @@ -895,8 +895,9 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
> >>  	if (unlikely(!pr))
> >>  		return -EINVAL;
> >>  
> >> -
> >>  	if (acpi_idle_suspend) {
> >> +		local_irq_disable();
> >> +		local_irq_enable();
> >>  		cpu_relax();
> >>  		return -EINVAL;
> >>  	}
> > 
> > May I say this is ugly?  Why can't we track the status of interrupts
> > properly here?
> 
> 
> 
> I agree. Just the irq_enable call should do the trick.
> Once the cpu enters idle via cpu_idle call, irqs are disabled. We
> need to enable them if acpi_idle_suspend is set.
> Else we'll see a hang during suspend.
> 
> The patch that was posted was just for workaround patch.
> I shall do some more testing with just irq_enable call
> and then shall post the fix which can be considered
> for inclusion.

I see.  OK, then, looking forward to seeing the final patch. :-)

Thanks,
Rafael
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