From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755942AbbLDJSS (ORCPT ); Fri, 4 Dec 2015 04:18:18 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:34780 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755662AbbLDJSN (ORCPT ); Fri, 4 Dec 2015 04:18:13 -0500 Date: Fri, 4 Dec 2015 10:18:10 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Peter Saunderson Cc: Guenter Roeck , Greg Kroah-Hartman , Arnd Bergmann , linux-kernel@vger.kernel.org Subject: Re: Erratic fan speed and little control kernel 4.2 Message-ID: <20151204091810.GP10982@pali> References: <5660A58B.7010305@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5660A58B.7010305@gmail.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter! On Thursday 03 December 2015 20:26:51 Peter Saunderson wrote: > Erratic fan speed and little control kernel 4.2 > > After upgrading to kernel 4.2 my CPU fan started speeding and slowing > without good reason even when the PC is idle. > > To stop erratic fan speed - reboot sometimes works. > > This bug has been bisected to commit > f989e55452c74b4f7b22c889b8ec9f1192aaeec4 There is very similar (or same) problem on desktop Dell Studio XPS 8100. See bug: https://bugzilla.kernel.org/show_bug.cgi?id=100121 In your long email is missing one important information: DMI information about your machine. Can you run dmidecode and send output? You were able to bisect problematic commit, are you able to do some additional test and debug root of this issue? In my opinion problem is in some SMM call, but without commenting code which calling it, step by step and testing is not possible to decide... -- Pali Rohár pali.rohar@gmail.com