From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756612AbZEVOyN (ORCPT ); Fri, 22 May 2009 10:54:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756279AbZEVOx7 (ORCPT ); Fri, 22 May 2009 10:53:59 -0400 Received: from mail-bw0-f174.google.com ([209.85.218.174]:37751 "EHLO mail-bw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754643AbZEVOx7 convert rfc822-to-8bit (ORCPT ); Fri, 22 May 2009 10:53:59 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=uLpUBCcZzPAqF11PIX2nsgDDJQuqna6rKnVLUBpuIroYJTwzOZTDHWwM1ZKlLuNp5q v6RUlneOgS+6l82OTvQQaqFX2/TqGlrY0gYFTxIvhRfAqq5z3s6bEqGRg+htkp1RF1OP 6wb56M8mypyhfTjbqtJDAHPzmh3GrqRYgIec4= MIME-Version: 1.0 In-Reply-To: <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> <20090522140930.GA26580@elf.ucw.cz> Date: Fri, 22 May 2009 16:53:59 +0200 Message-ID: <9ea470500905220753x6c2be25dq14422dff2acea422@mail.gmail.com> Subject: Re: [PATCH] Acer Aspire One Fan Control From: Borislav Petkov To: Pavel Machek Cc: Peter Feuerer , petkovbb@gmail.com, LKML , lenb@kernel.org, Matthew Garrett , Maxim Levitsky Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> >> 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. Yep, however we won't come that far with the current driver since it relinquishes control of the fan to the BIOS after a critical temp of 89° is reached. I'm still quite unpersuaded about that "magical" number since it is 1 degree below the high interval boundary of the juncture temperature of the Atom CPU. I would like to have a more reliable source for the allowed envelope based not only on the CPU but on the whole chipset but can't seem to find any data from Acer on that. >> 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_. I'm sure Peter wouldn't mind adding some other sysfs entries in future versions of the driver controlling exactly that. -- Regards/Gruss, Boris.