From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752472AbZEVGDd (ORCPT ); Fri, 22 May 2009 02:03:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751122AbZEVGD0 (ORCPT ); Fri, 22 May 2009 02:03:26 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:45725 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750880AbZEVGDZ (ORCPT ); Fri, 22 May 2009 02:03:25 -0400 Date: Tue, 19 May 2009 22:30:15 +0200 From: Pavel Machek To: Peter Feuerer Cc: petkovbb@gmail.com, LKML , lenb@kernel.org, Matthew Garrett , Maxim Levitsky Subject: Re: [PATCH] Acer Aspire One Fan Control Message-ID: <20090519203015.GA1362@ucw.cz> References: <20090428072519.GA12170@liondog.tnic> <1240913055.29860.14.camel@maxim-laptop> <1240950704.3781.12.camel@maxim-laptop> <20090503184617.GA3555@liondog.tnic> <20090509171432.GA31126@liondog.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 more I'm looking at the driver, the more I get annoyed by that >> user/kernel mode operation split. Remind me again why the driver should >> be loaded and not started automatically but the user should be required >> to activate it explicitly? > > 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. >> That's not so optimal, I'd say. The kernel module should _replace_ >> the userspace program, not work alongside it, since the last is flaky >> and unreliable, and this was the main reason the kernel module was >> introduced in the first place - to control the fan from kernel space, >> which is the more sane choice. > > The main reason to do this in kernel was the availabilty of atomic ec- > read and write functions. But I agree with you that either kernel or BIOS > should control the fan and not a userspace tool. I added the user mode > just because it wasn't really much more code than just an implementation > of the enable/disable functionality. Kernels crash, too, just like userspace does. It would still make sense to allow userspace to increase fan speed. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html