From FreeBSD (r227593, r307982):

From FreeBSD (r227593, r307982):
More and more RealTek controllers started to implement EEE feature.
Vendor driver seems to load a kind of firmware for EEE with
additional PHY fixups.  It is known that the EEE feature may need
ASPM support.  Unfortunately there is no documentation for EEE of
the controller so enabling ASPM may cause more problems.

The Realtek vendor drivers for FreeBSD and Linux also disable ASPM and
clock request.  While here, add a define for the ECPM (Enable Clock Power
Management) bit.

Tested by stsp@ and myself.
ok stsp@