[Phishing Risk] [External] Re: Does it make sense to create a centralized fan control module?

[John Wang]

On Wed, Jun 16, 2021 at 10:02 AM Heyi Guo <guoheyi at linux.alibaba.com> wrote:
>
> Hi All,
>
> Any comments for my questions at the top of this thread?
>
> Thanks,
>
> Heyi
>
>
> On 2021/6/11 上午9:23, Heyi Guo wrote:
> > Please ignore my early emails; only this one is the final version. I
> > must have misused some shortcut key to send the unfinished versions
> > while I wanted to save it locally...
> >
> > Sorry for the noise.
> >
> > Heyi
> >
> > On 2021/6/11 上午9:14, Heyi Guo wrote:
> >> Hi All,
> >>
> >> Right now fan related data like tacho and PWM is fetched in
> >> dbus-sensors, and published to d-bus as sensor data, while fan
> >> control is made in another module like pid-control, which can fetch
> >> data and set value via d-bus.
> >>
> >> In some common sense, we may think about putting all fan related work
> >> into one single module (which may be based on pid-control), i.e. it
> >> can read tacho and PWM from hardware directly, calculate the required

As I understand it, if you just want to bypass dbus and read pwm/tach
directly you can refer to this.
https://github.com/openbmc/openbmc/blob/master/meta-quanta/meta-gsj/recipes-phosphor/fans/phosphor-pid-control/config-2ssd.json#L6-L7

> >> PWM by some algorithm like PID, and then write to PWM hardware
> >> directly; the data will also be published to d-bus for other modules
> >> to consume, like fansensor from dbus-sensors.
> >>
> >> Does it make sense to do that? Or is there any reason for the current
> >> design?

I don't know why it's designed this way, but are you experiencing any problems?
According to our past experience, pid-control reads/writes pwm/tach
quite smoothly,
but pid-control has some trouble reading the temperature of some
sensors via dbus.(eg psusensors).
That's another topic...

> >>
> >> I'm new to OpenBMC and some of my understanding may be totally wrong.
> >>
> >> Looking forward to your expert advice.
> >>
> >> Thanks,
> >>
> >> Heyi