[External] Re: Questions regarding of phosphor-pid-control

[James Feist]

On 7/17/19 7:40 PM, Derek Lin23 wrote:
> Hi Patrick:
> 
>            The open-loop in this context is more likely to set duty of 
> PWM manually.
> 
>            For example, when reading a sensor above or below a certain 
> pre-defined temperature, then the duty of a PWM is revved up or lower to 
> the desired fan-speed.

You could use stepwise configurations to get this response. Here's an 
example of a lower clipping curve that when the reading of the sensor is 
20, outputs 50%, and when it reads 30 outputs 60%.

https://github.com/openbmc/entity-manager/blob/9813279b57359bd1602da236ff7d38bcc9a2fba4/configurations/R2000%20Chassis.json#L428

This is also configurable from the json I believe.


> 
>            More likely, PWM is set simply by the reading of a 
> temperature sensor. A map of temperature readings and PWM values can be 
> represented as an example.
> 
> Thank you,
> 
> Derek
> 
> *From:*Patrick Venture <venture at google.com>
> *Sent:* Tuesday, July 16, 2019 1:02 AM
> *To:* Derek Lin23 <dlin23 at lenovo.com>; James Feist 
> <james.feist at linux.intel.com>
> *Cc:* Yonghui YH21 Liu <liuyh21 at lenovo.com>; Harry Sung1 
> <hsung1 at lenovo.com>; OpenBMC Maillist <openbmc at lists.ozlabs.org>
> *Subject:* [External] Re: Questions regarding of phosphor-pid-control
> 
> On Tue, Jul 9, 2019 at 2:03 AM Derek Lin23 <dlin23 at lenovo.com 
> <mailto:dlin23 at lenovo.com>> wrote:
> 
>     Hi Patrick:
> 
> Adding the openbmc mailing list.  Please always include this mailing 
> list in your emails for archiving and later reference as well as opening 
> up the question to others.
> 
> Also adding James Feist as he co-maintains this codebase.
> 
>                This is Derek from Lenovo BMC team.
> 
>                We have some questions regarding ofphosphos-pid-control
>     <https://github.com/openbmc/phosphor-pid-control>, and we hope you
>     can provide some advice of the component.
> 
>                Currently, we would like to import phosphor-pid-control
>     as our thermal fan control module. After a brief study, we would
>     like to know if phosphor-pid-control can support open-loop and
>     event-triggered events?
> 
> I don't really know what open-loop means in this context.  Registering 
> for events, like?
> 
>     Thank you for your feedbacks,
> 
>     Derek
> 
>     ------------------------------------------------------------------------
> 
>     *Derek Lin*
>     Sr. BMC Engineer
>     8F,66, San Chong Rd., Nankang Software Park, Taipei.
>     Lenovo Taiwan
> 
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> 
>     Phone+886281707411
>     Emaildlin23 at lenovo.com <mailto:dlin23 at lenovo.com>
> 
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