Removing sensors on standby

[Matt Spinler]

On 6/11/2019 5:07 AM, Thaj wrote:
> Hi,
>
> As per current implementation of OpenBMC sensor architecture sensor is 
> added/removed when hwmon driver is probed/removed.
> But there are scenarios where hwmon driver is available but values are 
> not available. For example there are some sensors (VR, ADC, pwm tach) 
> in my system which are unavailable on BMC Standby(Host powered OFF). 
> Power to these devices are removed when host is off causing hwmon 
> driver to read a value 0. Please find the attached screenshot for 
> reference.
>
> Requirement is that, Sensor should be monitored only on host powered 
> ON state.
>
> How to handle sensors in this case?
>
> Is it a good idea to add a config file entry for this purpose 
> (something like REMOVE_ON_STANDBY) ?
>
If you are referring to the phosphor-hwmon repository (as opposed to 
dbus-sensors), I would accept a patch
that does that.

There is already a case in phosphor-hwmon where an OperationalStatus 
interface, with a boolean
Functional property, can get added.  Another idea would be to set that 
to not Functional in this case,
and have the web UI check that and display something different if it 
isn't functional.

In hindsight, having another property on the Sensor.Value interface to 
give the sensor status, like
working, broken, or not-available may have been a good idea.

> Regards,
> Thaj
>
>