RE: about phosphor pid control package

["Will Liang (梁永鉉)" <Will.Liang@quantatw.com>]

> -----Original Message-----
> From: Will Liang (梁永鉉)
> Sent: Friday, May 10, 2019 8:06 AM
> To: 'James Feist' <james.feist@linux.intel.com>; Patrick Venture
> <venture@google.com>
> Cc: OpenBMC Maillist <openbmc@lists.ozlabs.org>
> Subject: RE: about phosphor pid control package
> 
> 
> > On 5/9/19 7:43 AM, Patrick Venture wrote:
> > > On Wed, May 8, 2019 at 11:33 PM Will Liang (梁永鉉)
> > > <Will.Liang@quantatw.com> wrote:
> > >>
> > >> Hi,
> > >>
> > >>> -----Original Message-----
> > >>> From: Patrick Venture [mailto:venture@google.com]
> > >>> Sent: Thursday, May 9, 2019 12:36 AM
> > >>> To: Will Liang (梁永鉉) <Will.Liang@quantatw.com>
> > >>> Cc: OpenBMC Maillist <openbmc@lists.ozlabs.org>
> > >>> Subject: Re: about phosphor pid control package
> > >>>
> > >>> On Wed, May 8, 2019 at 6:46 AM Will Liang (梁永鉉)
> > >>> <Will.Liang@quantatw.com> wrote:
> > >>>>
> > >>>> Hi,
> > >>>>
> > >>>> I have a question about getFailSafeMode().
> > >>>>
> > >>>> Currently, only sensors that are defined as "temp" types can be
> > >>>> checked for
> > >>> failure.
> > >>>> I did not find any "fan" type sensors to check if the fan has failed.
> > >>>> Our project need to check the fan fail so  I want to add another
> > >>>> "fan" sensor
> > >>> type to check.
> > >>>
> > >>>
> > >>>
> > >>>>
> > >>>> Can I add one more "for loop" to check the fan sensor in
> > >>>> updateSensors()
> > >>> function in zone.cpp??
> > >>>>
> > >>>> for (const auto& t : _thermalInputs) {
> > >>>>      ........
> > >>>> }
> > >>>> for (const auto& t : _fanInputs)
> > >>>> {
> > >>>>      ........
> > >>>> }
> > >>>
> > >>> updateSensors is deliberately not talking to the fans because
> > >>> they're not considered inputs into the thermal config, they're
> > >>> controlled outputs -- the question I have is, what would you like
> > >>> to do if a
> > fan isn't responding?
> > >>> failsafemode drives the fans to a specific pre-defined speed to
> > >>> keep it from thermal issues.  If a fan is failing to respond, one
> > >>> can't drive it -- perhaps one can drive the others to some failsafe?
> > >>
> > >> If a fan fails, we need to enter the fail safe mode to increase the
> > >> other fan
> > duty.
> > >>
> > >>> If so, one needs to update the failsafe for a zone outside of the
> > >>> thermal sensors, but rather where the fans are checked (void
> > >>> PIDZone::updateFanTelemetry(void))
> > >>
> > >> I add following code into the PIDZone::updateFanTelemetry(void)
> > >> function
> > to check the fan fail.
> > >> If the fan fails, it will enter fail safe mode.
> > >>    if (sensor->getFailed())
> > >>    {
> > >>          failSafeSensors.insert(f);
> > >>    }
> > >>    else
> > >>    {
> > >>          // Check if it's in there: remove it.
> > >>      auto kt = _failSafeSensors.find(f);
> > >>      if (kt != _failSafeSensors.end())
> > >>    {
> > >>          failSafeSensors.erase(kt);
> > >>    }
> > >>
> > >> But one more question I have is that the above code can only check
> > >> if a
> > single fan has failed.
> > >
> > >> Our project needs to check for dual-fan failures. Do you have any
> > suggestions for checking the failure of the dual-fan?
> > >
> > > I'm not entirely certain what you mean.  You're saying a dual-fan is
> > > a fan that has two outputs but one input?
> >
> > If this is what you mean, on our systems we simply have a tach sensor
> > per tach in the fan, i.e. fan1a and fan1b. I think the above logic
> > would work for this issue.
I think someone may also need to check for one rotor fan fail, I will push the above code into gerrit

> I'm so sorry to make you misunderstand because of my unclear expression.
> The "dual-fan" means "Dual rotor fan" , two tachometer output one PWM
> input.
Our architecture is that both fan1a and fan1b fail (dual rotor fan failure) and then this situation is identified as one fan fail.

Would you have any suggestion or idea?

>
> > >
> > >>
> > >> Will
> > >>>>
> > >>>> BRs,
> > >>>> Will