linux-kernel - Re: [RFC PATCH 3/3] hwmon: (adt7475) temperature smoothing

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Date:   Tue, 2 May 2017 20:37:18 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3/3] hwmon: (adt7475) temperature smoothing

On 03/05/17 07:14, Guenter Roeck wrote:
> On Tue, May 02, 2017 at 05:45:36PM +1200, Chris Packham wrote:
>> When enabled temperature smoothing allows ramping the fan speed over a
>> configurable period of time instead of jumping to the new speed
>> instantaneously.
>>
>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>> ---
>>  Documentation/hwmon/adt7475 |   5 ++
>>  drivers/hwmon/adt7475.c     | 121 ++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 126 insertions(+)
>>
>> diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475
>> index 85dc9e17bdee..31b15cb910ea 100644
>> --- a/Documentation/hwmon/adt7475
>> +++ b/Documentation/hwmon/adt7475
>> @@ -114,6 +114,11 @@ at the minimum (i.e. auto_point1_pwm). This can be configured using the
>>  pwm[1-*]_min sysfs attribute. A value of 0 means the fans will shut off. A
>>  value of 1 means the fans will run at auto_point1_pwm.
>>
>> +The responsiveness of the ADT747x to temperature changes can be configured.
>> +This allows smoothing of the fan speed transition. To enable temperature
>> +smoothing used the temp[1-*]_smoothing_enable sysfs attribute. To set the
>> +transition time set the value in ms in the temp[1-*]_smoothing sysfs attribute.
>> +
> Does this require two attributes, or can setting '0' for temp[1-*]_smoothing
> be used to disable it ?
>

One attribute could be made to work. I was following asc7621.c but from 
a usability perspective having to set the two attributes is not 
particularly convenient. The only argument for separating them is to 
allow smoothing at whatever the hardware default is.