From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756302AbaELK1R (ORCPT ); Mon, 12 May 2014 06:27:17 -0400 Received: from smtprelay01.ispgateway.de ([80.67.31.28]:49982 "EHLO smtprelay01.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751864AbaELK1Q (ORCPT ); Mon, 12 May 2014 06:27:16 -0400 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> <20140506105029.GC2858@e102654-lin.cambridge.arm.com> Message-ID: X-Mailer: http://www.courier-mta.org/cone/ From: Peter Feuerer To: Javi Merino Cc: LKML , Andrew Morton , Zhang Rui , Andreas Mohr , Borislav Petkov Subject: Re: [PATCH v3 4/6] acerhdf: Use bang-bang thermal governor Date: Mon, 12 May 2014 12:27:08 +0200 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="US-ASCII" Content-Disposition: inline Content-Transfer-Encoding: 7bit X-Df-Sender: NDA0MDk0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Javi, Javi Merino writes: > 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; Yes, sounds good. What about trip == 1? This is a valid trip point for acerhdf (critical) and one could argue, that it has a valid hysteresis of 0. - Thus EINVAL would be wrong here. thanks and kind regards, --peter;