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The "reverse RMII" protocol name is a personal invention, derived from "reverse MII". Just like MII, RMII is an asymmetric protocol in that a PHY behaves differently than a MAC. In the case of RMII, for example: - the 50 MHz clock signals are either driven by the MAC or by an external oscillator (but never by the PHY). - the PHY can transmit extra in-band control symbols via RXD[1:0] which the MAC is supposed to understand, but a PHY isn't. The "reverse MII" protocol is not standardized either, except for this web document: https://www.eetimes.com/reverse-media-independent-interface-revmii-block-architecture/# In short, it means that the Ethernet controller speaks the 4-bit data parallel protocol from the perspective of a PHY (it acts like a PHY). This might mean that it implements clause 22 compatible registers, although that is optional - the important bit is that its pins can be connected to an MII MAC and it will 'just work'. In this discussion thread: https://lore.kernel.org/netdev/20210201214515.cx6ivvme2tlquge2@skbuf/ we agreed that it would be an abuse of terms to use the "RevMII" name for anything than the 4-bit parallel MII protocol. But since all the same concepts can be applied to the 2-bit Reduced MII protocol as well, here we are introducing a "Reverse RMII" protocol. This means: "behave like an RMII PHY". Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.