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SubjectRe: [PATCH v3 3/4] net: stmmac: register parent MDIO node for sun8i-h3-emac
On Mon, Aug 21, 2017 at 04:23:21PM +0200, Andrew Lunn wrote:
> > All muxes are mostly always represented the same way afaik, or do you
> > want to simply introduce a new compatible / property?
>
> + mdio-mux {
> + compatible = "allwinner,sun8i-h3-mdio-switch";
> + mdio-parent-bus = <&mdio_parent>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + internal_mdio: mdio@1 {
> reg = <1>;
> - clocks = <&ccu CLK_BUS_EPHY>;
> - resets = <&ccu RST_BUS_EPHY>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> + int_mii_phy: ethernet-phy@1 {
> + compatible = "ethernet-phy-ieee802.3-c22";
> + reg = <1>;
> + clocks = <&ccu CLK_BUS_EPHY>;
> + resets = <&ccu RST_BUS_EPHY>;
> + phy-is-integrated;
> + };
> + };
> + mdio: mdio@0 {
> + reg = <0>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> };
>
> Hi Maxim
>
> Anybody who knows the MDIO-mux code/binding, knows that it is a run
> time mux. You swap the mux per MDIO transaction. You can access all
> the PHY and switches on the mux'ed MDIO bus.
>
> However here, it is effectively a boot-time MUX. You cannot change it
> on the fly. What happens when somebody has a phandle to a PHY on the
> internal and a phandle to a phy on the external? Does the driver at
> least return -EINVAL, or -EBUSY? Is there a representation which
> eliminates this possibility?
>

Exactly you can change it on the fly, but you need to reset the MAC for enabling the new configuration.
The stmmac driver does not handle mdio-mux. It is why I have a patch which automaticly select parent MDIO node of the PHY node.

For representation we could keep the current. (With a big comment stating that it is a switch)

We can also add a mdio-switch type node, or add a mdio-switch property to mdio-mux.

Regards

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