phosphor-hwmon + phosphor-fan: Fan functional properties are mismatched when unplug fan

[Thu Nguyen]

Hi,


In the current code of phosphor-hwmon, when flag 
--enable-update-functional-on-fail is set. The fan functional DBus 
property in sensors interface will be set to false when unplug fans 
(FAN4_2).

~# busctl get-property xyz.openbmc_project.Hwmon-1644477290.Hwmon1 
/xyz/openbmc_project/sensors/fan_tach/FAN4_2 
xyz.openbmc_project.State.Decorator.OperationalStatus Functional
b false

AND the fan Value properties will keep the latest reading value before 
unplug.

~# busctl get-property xyz.openbmc_project.Hwmon-1644477290.Hwmon1 
/xyz/openbmc_project/sensors/fan_tach/FAN4_2 
xyz.openbmc_project.Sensor.Value Value

d 4794

~# busctl get-property xyz.openbmc_project.Hwmon-1644477290.Hwmon1 
/xyz/openbmc_project/sensors/fan_tach/FAN4_2 
xyz.openbmc_project.Sensor.Value Value
d 4794

This cause phosphor-fan-monitor failed to detect the fan failure so the 
fan functional are wrong.

busctl get-property xyz.openbmc_project.Inventory.Manager 
/xyz/openbmc_project/inventory/system/chassis/motherboard/FAN4_2 
xyz.openbmc_project.State.Decorator.OperationalStatus Functional
b true

Should phosphor-hwmon keep updating the fan value Dbus properties with 
error code when the fans is nonfunctional? Or phosphor-fan-monitor 
should also check the fan functional in sensor interface to update fan 
functional in inventory interface?


Regards.

Thu Nguyen.