From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751521AbaEQVJp (ORCPT ); Sat, 17 May 2014 17:09:45 -0400 Received: from cantor2.suse.de ([195.135.220.15]:35781 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210AbaEQVJo (ORCPT ); Sat, 17 May 2014 17:09:44 -0400 Date: Sat, 17 May 2014 23:09:40 +0200 From: Jean Delvare To: Guenter Roeck Cc: Pali =?ISO-8859-1?B?Um9o4XI=?= , linux-kernel@vger.kernel.org Subject: Re: Dell Latitude E6440 & i8k Message-ID: <20140517230940.25c36f07@endymion.delvare> In-Reply-To: <53777F72.3000907@roeck-us.net> References: <201405162037.41782@pali> <20140516211117.0c766287@endymion.delvare> <53777F72.3000907@roeck-us.net> Organization: SUSE Linux X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 17 May 2014 08:25:38 -0700, Guenter Roeck wrote: > On 05/16/2014 12:11 PM, Jean Delvare wrote: > > Load the i8k driver with fan_mult=1. > > Would it make sense to change the default multiplier to 1 ? > Lots of people have problems with it, and trying to figure out > affected machines one by one would be an all but impossible task. That would cause a regression on many (presumably older) machines. I doubt this is acceptable. One option would be to use the ACPI year to change the default, if indeed all new machines need fan_mult=1. I don't know if this is the case. One this I had in mind was auto-detecting the scaling factor. AFAIK only 30 and 1 are possible values, so any value above ~300 would imply scaling factor of 1 (30 would make it > 9000 RPM which is unrealistic.) But I don't know if we can actually do that, as such a simple heuristic could easily fail is the fan is stopped (30 * 0 == 1 * 0) or if the returned raw speed is temporarily unreliable for whatever reason. I have to admit that working on a reverse engineered driver for hardware I don't even have isn't quite at the top of my to-do list. -- Jean Delvare SUSE L3 Support