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| author | Vladimir Oltean <vladimir.oltean@nxp.com> | 2021-06-04 17:01:48 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-06-07 12:20:18 -0700 |
| commit | c858d436be8b949c368de0e079084acaff3d4aaf (patch) | |
| tree | 34550b596f608cbdca616ca750b4d08a10a64172 /Documentation/devicetree/bindings/net/ethernet-controller.yaml | |
| parent | 1a42624aecba438f1d114430a14b640cdfa51c87 (diff) | |
net: phy: introduce PHY_INTERFACE_MODE_REVRMII
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>
Diffstat (limited to 'Documentation/devicetree/bindings/net/ethernet-controller.yaml')
| -rw-r--r-- | Documentation/devicetree/bindings/net/ethernet-controller.yaml | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml index e8f04687a3e0..d97b561003ed 100644 --- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml +++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml @@ -68,6 +68,7 @@ properties: - tbi - rev-mii - rmii + - rev-rmii # RX and TX delays are added by the MAC when required - rgmii |