Hi Sergei,

   The subject also could be more concise...

I'll think about it. Thank you!

    Not at all so common as I thought! Only 4 drivers use mdio-bitbang,
2 of them are for the Renesas SoCs...

Yes.

    Do yuo have R-Car V3H at hand, by chance? It does have a GEther
controler used for booting up...

I'm sorry. I don't have it.
There is a SILK board of R-Car Gen2 in the office where I work.
But I can't go to the office now because of the COVID-19 problem. 
If I can go to the office, I'll bring home the SILK board.

Well, due to usually using NFS the EtherAVB (and Ether too) driver is
probably alwaysbuilt in-kernel...

Yes. I think so, too.
Since it is necessary to reduce the Image size for embedded use, I found
this problem when changing to a module and testing.

   Trim your messages after your goodbye. That original message stuff
typically isn't tolerated in the Linux mailing lists, nearly the same as
top-posting...

OK. Thanks.

Thanks & Best Regards,
Yuusuke Ashizuka [off-list ref]