FruDevice/Entity Manager vs hwmon

Mahesh Kurapati mahesh.kurapati at
Sun May 30 05:13:48 AEST 2021


I want to define temperature sensors, fans and PSUs for our new platform.  Going through the documentation and sources,  I understand that there are two approaches.  One is to define them with the same i2c path as mentioned in the device tree as part of the hwmon configuration, and the other approach is to define a json file with appropriate probe in the entity-manager/configurations folder so that the FruDevice and Entity Manager apps detect the devices as per the probe and create the matching dbus objects, while the dbus-sensors do the instrumentation.  With entity manager approach I understand that the i2c devices are created/probed when they are detected.  My questions is we don't need the device defined in the device tree file if I go by this approach? I understand that this helps the dynamic detection of the FRU.  Also we have LM73, and other temp sensor TMP431c that is not defined in the FruDevice record map.  Next question is do I need to add support for the LM73 tmp75MP431C and other one in the FruDevice so that it gets created properly? Can I use any existing strings/mapping for these sensors?  This is not needed if I define the entries in the device tree, and integrate with hwmon I have everything needed.  I see that hwmon and FruDevice/Entity Manager/dbus-sensors provide similar functionality.  Can I have both of these services running at the same time on the BMC? Will it cause any conflicts?  Please help me understand.

Thank you,
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