From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753660AbcFMSaV (ORCPT ); Mon, 13 Jun 2016 14:30:21 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36420 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992AbcFMSaS (ORCPT ); Mon, 13 Jun 2016 14:30:18 -0400 From: Pali =?utf-8?q?Roh=C3=A1r?= To: Thorsten Leemhuis Subject: Re: [PATCH] dell-smm-hwmon: Cache fan_type() calls and use fan_status() for fan detection Date: Mon, 13 Jun 2016 20:30:14 +0200 User-Agent: KMail/1.13.7 (Linux/3.13.0-86-generic; KDE/4.14.2; x86_64; ; ) Cc: Jan C Peters , David =?utf-8?q?Santamar=C3=ADa_Rogado?= , Peter Saunderson , Jean Delvare , Guenter Roeck , Tolga Cakir , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org References: <1463842001-17785-1-git-send-email-pali.rohar@gmail.com> <201605271521.10294@pali> In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart5756580.YL7Ru7Upol"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <201606132030.14769@pali> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nextPart5756580.YL7Ru7Upol Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Monday 30 May 2016 13:45:51 Thorsten Leemhuis wrote: > Pali Roh=C3=A1r wrote on 27.05.2016 15:21: > > On Friday 27 May 2016 15:05:54 Thorsten Leemhuis wrote: > >> Pali Roh=C3=A1r wrote on 27.05.2016 12:45: > >> So I tried a few things > >> and came to the conclusion: the problem shows up as soon as > >> i8k_get_fan_type() (introduced in f989e55452) is called somewhere. > >=20 > > So, once kernel call i8k_get_fan_type() function, then fan speed > > going up/down? >=20 > Yes. >=20 > > To make sure that this is root of your problem, can you take some > > older kernel version (where is i8k working fine) and try to > > patch+call that i8k_get_fan_type() function? To check that > > something else cannot interference with it... >=20 > I just tried with 3.19.8 (had to install a older distro first :-/ ), > where the problem does not show up (I verified just to be sure). Then > I applied below patch and voila: the fan speed starts going up/down. >=20 > IOW: From what I can see that SMM call that i8k_get_fan_type() > triggers the problem on my Studio 8000 >=20 > CU, knurd >=20 Thank you for your testing! I believe now we definitely know root of=20 this problem. It is buggy Dell BIOS/SMM code and we need to avoid=20 calling I8K_SMM_GET_FAN_TYPE on affected buggy Dell machines. =2D-=20 Pali Roh=C3=A1r pali.rohar@gmail.com --nextPart5756580.YL7Ru7Upol Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlde+7YACgkQi/DJPQPkQ1IAKgCfdm9fagkIg8OpI4hXcv3FSzoQ 17YAn1ZmX6QkcmtbNTdXR2zLYAuwUlzo =3sxN -----END PGP SIGNATURE----- --nextPart5756580.YL7Ru7Upol--