Although, there is no specific errata available for adding fixup
specific to lan78xx USB dongle, we have added the fixup for handing
specific configurations to ensure the PHY operates correctly with the
MAC. In this case while transmitting from MAC to PHY the device does
not add the delay locally at its TX input pins. It expects the TXC
delay to be provided by on-chip MAC. Since the delay calculated in this
case is specific to the lan78xx USB dongle it is not possible to use
this fixup for interfacing with generic MAC.

Have you tried PHY_INTERFACE_MODE_RGMII_TXID when connecting to the
PHY? The four PHY_INTERFACE_MODE_RGMII_* values are the official way
to ask the PHY to insert delays, or not. If that is all you are doing,
i don't think you need these fixups at all.

quoted

Please give me a details explanation why this fixup will not be
applied to other instances of this PHY in the system.

As stated above, the TXC delay calculated for the PHY is specific to
the lan78xx on-chip MAC. This delay ensures that both the phy and MAC
clock delay timing is met. Any other MACs connected will need a
different delay values to be synchronized with MAC and hence these
instances will get failed.

You did not answer my question. Show me the code path which prevents
this being applied to other PHYs. Is there a comparison to netdev
somewhere when applying the fixup? Give me the file:line number.

	  Andrew