I managed to enable the DEV_OFF_N functionality by programming an additional double word to the iNVM but I am not quite sure whether I did it properly and we do have the latest eepromARMtool as well as iNVM setting files available.
Programming the following double word into iNVM enables DEV_OFF_N incl. IEEE PHY power down:
83003C19
Does that make sense at all?
Even though table 2-8 of the i210 data sheet on miscellaneous pins states DEV_OFF_N being an asynchronous pin it seems to require a full PCIe hardware reset as well to actually really power off. I guess that is just the way it is supposed to be, correct?
The eepromARMtool we have is version 0.6.7 and the iNVM setting files are the v0.6 ones.
Are those current?