From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Chris Packham To: Guenter Roeck CC: "linux-hwmon@vger.kernel.org" , "jdelvare@suse.com" , Jonathan Corbet , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH v2 2/3] hwmon: (adt7475) fan stall prevention Date: Wed, 3 May 2017 20:44:52 +0000 Message-ID: References: <20170503004009.23769-1-chris.packham@alliedtelesis.co.nz> <20170503004009.23769-3-chris.packham@alliedtelesis.co.nz> <20170503161044.GA9471@roeck-us.net> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 List-ID: On 04/05/17 04:10, Guenter Roeck wrote:=0A= > On Wed, May 03, 2017 at 12:40:08PM +1200, Chris Packham wrote:=0A= >> By default adt7475 will stop the fans (pwm duty cycle 0%) when the=0A= >> temperature drops past Tmin - hysteresis. Some systems want to keep the= =0A= >> fans moving even when the temperature drops so add new sysfs attributes= =0A= >> that configure the enhanced acoustics min 1-3 which allows the fans to= =0A= >> run at the minimum configure pwm duty cycle.=0A= >>=0A= >> Signed-off-by: Chris Packham =0A= >> ---=0A= >> Changes in v2:=0A= >> - use pwmN_stall_dis as the attribute name. I think this describes the p= urpose=0A= >> pretty well. I went with a new attribute instead of overloading=0A= >> pwmN_auto_point1_pwm so this doesn't affect existing users.=0A= >>=0A= >> Documentation/hwmon/adt7475 | 5 +++++=0A= >> drivers/hwmon/adt7475.c | 50 ++++++++++++++++++++++++++++++++++++++= +++++++=0A= >> 2 files changed, 55 insertions(+)=0A= >>=0A= >> diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475= =0A= >> index 0502f2b464e1..63507402cd4f 100644=0A= >> --- a/Documentation/hwmon/adt7475=0A= >> +++ b/Documentation/hwmon/adt7475=0A= >> @@ -109,6 +109,11 @@ fan speed) is applied. PWM values range from 0 (off= ) to 255 (full speed).=0A= >> Fan speed may be set to maximum when the temperature sensor associated = with=0A= >> the PWM control exceeds temp#_max.=0A= >>=0A= >> +At Tmin - hysteresis the PWM output can either be off (0% duty cycle) o= r at the=0A= >> +minimum (i.e. auto_point1_pwm). This behaviour be configured using the= =0A= >> +pwm[1-*]_stall_dis sysfs attribute. A value of 0 means the fans will sh= ut off.=0A= >=0A= > That is really an awkward attribute name. I'll have to think about this s= ome=0A= > more.=0A= =0A= I agree. The other thing I considered was "halt" and using inverted =0A= logic so halt =3D=3D 1 reflected the HW default of allowing fans to stop.= =0A= =0A=