netdev - Re: C45 support and mdiobus

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Message-ID: <20180809150309.GA20006@lunn.ch>
Date:   Thu, 9 Aug 2018 17:03:09 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: C45 support and mdiobus_scan

On Thu, Aug 09, 2018 at 02:54:11PM +0100, Jose Abreu wrote:
> Hi All,
> 
> I'm preparing to add support for 10G in stmmac and I noticed that
> Generic 10G PHY needs C45 support. Digging through the
> registration callbacks for phy that are used in stmmac I reached
> to mdiobus_scan() and the following call:
> 
> phydev = get_phy_device(bus, addr, false);
> 
> The last parameter is "is_c45", and is always being set to false ...
> 
> Does this mean that I can't use the Generic 10G PHY in stmmac? I
> don't mind link being fixed for 10G for now.

Hi Jose

So far, all MACs which support 10G have used phy-handle to point to a
PHY on am MDIO bus, and that PHY uses .compatible =
"ethernet-phy-ieee802.3-c45". of_mdiobus_register() will then find the
PHY and register it. You really should try to follow this, if you can.

> (Notice I'm using a PCI based setup so no DT bindings can help me
> for this).

That is not necessarily true. Take a look at:

arch/arm/boot/dts/imx6qdl-zii-rdu2.dtsi

&pcie {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_pcie>;
        reset-gpio = <&gpio7 12 GPIO_ACTIVE_LOW>;
        status = "okay";

        host@0 {
                reg = <0 0 0 0 0>;

                #address-cells = <3>;
                #size-cells = <2>;

                i210: i210@0 {
                        reg = <0 0 0 0 0>;
                };
        };
};

The PCIe core will look in the device tree and when it creates the
platform device for the i210 on the pcie bus, it points
pdev->dev.of_node at this node. So long as you are using a platform
with DT, you can do this. I hope you are not using x86..

     Andrew