linux-kernel - changing the default cpufreq governor freezes laptop on suspend

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Message-ID: <20100723011514.GD19985@gamma.logic.tuwien.ac.at>
Date:	Fri, 23 Jul 2010 10:15:14 +0900
From:	Norbert Preining <preining@...ic.at>
To:	linux-kernel@...r.kernel.org
Subject: changing the default cpufreq governor freezes laptop on suspend

Dear all,

(please Cc)

some time ago I switched from 2.6.35-rc1 to -rc2 and about the same time
I regularly got problems with suspend to ram. I first thought that this
is a graphics card issue 
(see http://marc.info/?l=linux-kernel&m=127582534931581&w=2)
but it turned out that using echo mem > /sys/power/state works very
reliable.

I finally got around to check the scripts of pm-utils managing the
suspend process here on Debian/sid, and I found that one of the
scripts, before going to sleep, changes the default cpufreq governor
to performance, doing in principle:
	cat /sys/devices/system/cpu/cpuN/cpufreq/scaling_governor > savedstate
	echo "performance" > /sys/.....
Interestingly, as soon as I disabled these two line the suspend process
became again as stable as before using pm-utils, and as stable as the
echo mem method.

My laptop is intel core2:
Intel(R) Core(TM)2 Duo CPU     P9500  @ 2.53GHz
running Debian/sid, on self compiled git kernels pulled from Linus' repo.

Please let me know what further information I can provide, or how to help

Best wishes

Norbert
------------------------------------------------------------------------
Norbert Preining            preining@...ist.ac.jp, logic.at, debian.org}
JAIST, Japan                                 TeX Live & Debian Developer
DSA: 0x09C5B094   fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
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