From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934807AbaEFKui (ORCPT ); Tue, 6 May 2014 06:50:38 -0400 Received: from service87.mimecast.com ([91.220.42.44]:48808 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934660AbaEFKuh convert rfc822-to-8bit (ORCPT ); Tue, 6 May 2014 06:50:37 -0400 Date: Tue, 6 May 2014 11:50:29 +0100 From: Javi Merino To: Peter Feuerer Cc: LKML , Andrew Morton , Zhang Rui , Andreas Mohr , Borislav Petkov Subject: Re: [PATCH v3 4/6] acerhdf: Use bang-bang thermal governor Message-ID: <20140506105029.GC2858@e102654-lin.cambridge.arm.com> References: <1398561815-22033-1-git-send-email-peter@piie.net> <1399139966-10625-1-git-send-email-peter@piie.net> <1399139966-10625-5-git-send-email-peter@piie.net> MIME-Version: 1.0 In-Reply-To: <1399139966-10625-5-git-send-email-peter@piie.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginalArrivalTime: 06 May 2014 10:50:39.0100 (UTC) FILETIME=[04B36BC0:01CF6919] X-MC-Unique: 114050611503510301 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On Sat, May 03, 2014 at 06:59:24PM +0100, Peter Feuerer wrote: > acerhdf has been doing an on-off fan control using hysteresis by > post-manipulating the outcome of thermal subsystem trip point handling. > This patch enables acerhdf to use the bang-bang governor, which is > intended for on-off controlled fans. > > Cc: Andrew Morton > CC: Zhang Rui > Cc: Andreas Mohr > Cc: Borislav Petkov > Cc: Javi Merino > Signed-off-by: Peter Feuerer > --- > drivers/platform/x86/Kconfig | 2 +- > drivers/platform/x86/acerhdf.c | 34 +++++++++++++++++++++++++++++----- > 2 files changed, 30 insertions(+), 6 deletions(-) > > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig > index 27df2c5..0c15d89 100644 > --- a/drivers/platform/x86/Kconfig > +++ b/drivers/platform/x86/Kconfig > @@ -38,7 +38,7 @@ config ACER_WMI > > config ACERHDF > tristate "Acer Aspire One temperature and fan driver" > - depends on THERMAL && ACPI > + depends on ACPI && THERMAL_GOV_BANG_BANG > ---help--- > This is a driver for Acer Aspire One netbooks. It allows to access > the temperature sensor and to control the fan. > diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c > index 176edbd..afaa849 100644 > --- a/drivers/platform/x86/acerhdf.c > +++ b/drivers/platform/x86/acerhdf.c > @@ -50,7 +50,7 @@ > */ > #undef START_IN_KERNEL_MODE > > -#define DRV_VER "0.5.30" > +#define DRV_VER "0.5.31" > > /* > * According to the Atom N270 datasheet, > @@ -259,6 +259,14 @@ static const struct bios_settings_t bios_tbl[] = { > > static const struct bios_settings_t *bios_cfg __read_mostly; > > +/* > + * this struct is used to instruct thermal layer to use bang_bang instead of > + * default governor for acerhdf > + */ > +static struct thermal_zone_params acerhdf_zone_params = { > + .governor_name = "bang_bang", > +}; > + > static int acerhdf_get_temp(int *temp) > { > u8 read_temp; > @@ -440,6 +448,15 @@ static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip, > return 0; > } > > +static int acerhdf_get_trip_hyst(struct thermal_zone_device *thermal, int trip, > + unsigned long *temp) > +{ > + if (trip == 0) > + *temp = fanon - fanoff; > + > + return 0; > +} > + I think you should only return 0 if you've updated the temperature. Otherwise you're telling the calling function that everything went all right but you may be leaving garbage in *temp. What about if (trip != 0) return -EINVAL; *temp = fanon - fanoff; return 0; Cheers, Javi