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 <a...@linux-foundation.org> > CC: Zhang Rui <rui.zh...@intel.com> > Cc: Andreas Mohr <a...@lisas.de> > Cc: Borislav Petkov <b...@suse.de> > Cc: Javi Merino <javi.mer...@arm.com> > Signed-off-by: Peter Feuerer <pe...@piie.net> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/