From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754604AbcE0NVQ (ORCPT ); Fri, 27 May 2016 09:21:16 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:34362 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754198AbcE0NVO (ORCPT ); Fri, 27 May 2016 09:21:14 -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: Fri, 27 May 2016 15:21:10 +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> <201605271245.47383@pali> <01084692-618a-31db-76f8-60176d1cd2cc@leemhuis.info> In-Reply-To: <01084692-618a-31db-76f8-60176d1cd2cc@leemhuis.info> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1642232.Jl8UzZsv1J"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <201605271521.10294@pali> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nextPart1642232.Jl8UzZsv1J Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Friday 27 May 2016 15:05:54 Thorsten Leemhuis wrote: > Pali Roh=C3=A1r wrote on 27.05.2016 12:45: > > [=E2=80=A6] > > Looks like there are two different problems with dell-smm-hwmon > > driver: 1) Fan speed going randomly up and down without system > > freeze [=E2=80=A6] > > So for problem 1) I need to know: > >=20 > > * Is it regression? [=E2=80=A6] >=20 > Yes, it is known to be a regression from f989e55452, as identified > by Jan in https://bugzilla.kernel.org/show_bug.cgi?id=3D100121#c13 >=20 > I just verified and reverted that change on top of 4.6; the > problem with the fan speed indeed goes away. Ok, thanks for testing! > 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. So, once kernel call i8k_get_fan_type() function, then fan speed going=20 up/down? Even if it was called only at once? Can you confirm it? Caching=20 patch cause that for each fan that function is called exactly one time. If this is problem, we can probably create DMI list of machines which do=20 not like i8k_get_fan_type() call and disable it for them. To make sure that this is root of your problem, can you take some older=20 kernel version (where is i8k working fine) and try to patch+call that=20 i8k_get_fan_type() function? To check that something else cannot=20 interference with it... > Find below the minimal patch I could come up to that makes the fan > act normal on the Studio 8000 I have here (it's just meant as a > reference and not meant to be applied, as it leaves unused functions > around). Patch just make sure that i8k_get_fan_type() is never called. =2D-=20 Pali Roh=C3=A1r pali.rohar@gmail.com --nextPart1642232.Jl8UzZsv1J 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) iEYEABECAAYFAldIScYACgkQi/DJPQPkQ1KDwQCgns3iN+KEW01C4tvfzKBPey/A IPMAnjM4NXZWkw8pNF0FwjpBxPp1I57P =H6mj -----END PGP SIGNATURE----- --nextPart1642232.Jl8UzZsv1J--