From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755815AbZEVOJt (ORCPT ); Fri, 22 May 2009 10:09:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756486AbZEVOJf (ORCPT ); Fri, 22 May 2009 10:09:35 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:52802 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756965AbZEVOJd (ORCPT ); Fri, 22 May 2009 10:09:33 -0400 Date: Fri, 22 May 2009 16:09:30 +0200 From: Pavel Machek To: Borislav Petkov Cc: Peter Feuerer , petkovbb@gmail.com, LKML , lenb@kernel.org, Matthew Garrett , Maxim Levitsky Subject: Re: [PATCH] Acer Aspire One Fan Control Message-ID: <20090522140930.GA26580@elf.ucw.cz> References: <1240913055.29860.14.camel@maxim-laptop> <1240950704.3781.12.camel@maxim-laptop> <20090503184617.GA3555@liondog.tnic> <20090509171432.GA31126@liondog.tnic> <20090519203015.GA1362@ucw.cz> <9ea470500905220450s2367f8a1uc2b19a9466ea8509@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9ea470500905220450s2367f8a1uc2b19a9466ea8509@mail.gmail.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > >> The idea of not starting the module in kernel mode was from Matthew. And > >> he stated that it could harm the hardware when software controls the fan > >> instead of the BIOS. It may also be possible, that the warranty gets > > > > Well... hw is usually designed to protect itself. > > It seems like the fan in the aspire one's is used for cooling the > surrounding devices too and while the thermal envelope of the CPU is > much wider, the peripherals are much more susceptible to temperatures > outside of their allowed operating range. That's why currently the > driver lets the BIOS control the fan since its settings are most > conservative. Yep, I don't disagree. But I strongly suspect that if you force the fan off and overheat the machine, it will shut down in hardware before doing any damage. > > Kernels crash, too, just like userspace does. It would still make > > sense to allow userspace to increase fan speed. > > Well, if the kernel is dead, userspace has already died > too. Yep. > the module can still be toggled on/off from sysfs. Actually, empirically > measured, there seem to be three states of the fan: off, on and on-max > where you can hear it rotating at max RPM. The kernel module can handle > those completely if you know the respective ACPI EC commands and there's > no need for userspace daemon, IMHO. It would be still nice to let the userspace lower the trip points for maximum flexibility. No need for userspace _daemon_. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html