linux-kernel - [patch 0/2] suspend/resume regression fixes

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Date:	Sat, 22 Sep 2007 22:29:04 -0000
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...l.org>,
	Ingo Molnar <mingo@...e.hu>, Len Brown <lenb@...nel.org>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: [patch 0/2] suspend/resume regression fixes

Sorry, it took me quite a while to realize the real root cause of the
VAIO - and probably many other machines - suspend/resume regressions,
which were unearthed by the dyntick / clockevents patches.

We disable a lot of ACPI/BIOS functionality during suspend, but we
keep the lower idle C-states functionality active across
suspend/resume. It seems that this causes trouble with certain BIOSes,
but I assume that the problem is more wide spread and just not
surfacing due to the various scenarios in which a machine goes into
suspend/resume. I spent some quality time to figure out a set of debug
mechanisms, which did not influence the problem. So it is quite likely
that a lot of machines might be affected by this, but due to the
configuration, interrupt scenarios, .... the problem just does
not show up. 

My final enlightment was, when I removed the ACPI processor module,
which controls the lower idle C-states, right before resume; this
worked fine all the time even without all the workaround hacks.

I really hope that this two patches finally set an end to the "jinxed
VAIO heisenbug series", which started when we removed the periodic
tick with the clockevents/dyntick patches.

Venki, can you please add the analogous fix to the cpuidle patch set ?

Thanks,

	tglx
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