Re: [PATCH net-next 1/3] dt-bindings: net: tja11xx: use reverse-mode to instead of rmii-refclk-in

[Andrew Lunn <andrew@lunn.ch>]

On Thu, Aug 15, 2024 at 01:51:24PM +0800, Wei Fang wrote:
> Per the MII and RMII specifications, for the standard RMII mode,
> the REF_CLK is sourced from MAC to PHY or from an external source.
> For the standard MII mode, the RX_CLK and TX_CLK are both sourced
> by the PHY. But for TJA11xx PHYs, they support reverse mode, that
> is, for revRMII mode, the REF_CLK is output, and for revMII mode,
> the TX_CLK and RX_CLK are inputs to the PHY.
> Previously the "nxp,rmii-refclk-in" was added to indicate that in
> RMII mode, if this property present, REF_CLK is input to the PHY,
> otherwise it is output. This seems inappropriate now. Firstly, for
> the standard RMII mode, REF_CLK is originally input, and there is
> no need to add the "nxp,rmii-refclk-in" property to indicate that
> REF_CLK is input. Secondly, this property is not generic for TJA
> PHYs, because it cannot cover the settings of TX_CLK and RX_CLK in
> MII mode. Therefore, add new property "nxp,reverse-mode" to instead
> of the "nxp,rmii-refclk-in" property.

Please could you add some justification why using
PHY_INTERFACE_MODE_REVRMII is not possible.

	Andrew