linux-kernel - Re: [PATCH v2] net: macb: do not scan PHYs manually

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Date:	Thu, 28 Apr 2016 23:23:15 +0200
From:	Andrew Lunn <andrew@...n.ch>
To:	Josh Cartwright <joshc@...com>
Cc:	Nathan Sullivan <nathan.sullivan@...com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Florian Fainelli <f.fainelli@...il.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Subject: Re: [PATCH v2] net: macb: do not scan PHYs manually

On Thu, Apr 28, 2016 at 04:03:57PM -0500, Josh Cartwright wrote:
> On Thu, Apr 28, 2016 at 08:59:32PM +0200, Andrew Lunn wrote:
> > On Thu, Apr 28, 2016 at 01:55:27PM -0500, Nathan Sullivan wrote:
> > > On Thu, Apr 28, 2016 at 08:43:03PM +0200, Andrew Lunn wrote:
> > > > > I agree that is a valid fix for AT91, however it won't solve our problem, since
> > > > > we have no children on the second ethernet MAC in our devices' device trees. I'm
> > > > > starting to feel like our second MAC shouldn't even really register the MDIO bus
> > > > > since it isn't being used - maybe adding a DT property to not have a bus is a
> > > > > better option?
> > > > 
> > > > status = "disabled"
> > > > 
> > > > would be the unusual way.
> > > > 
> > > >       Andrew
> > > 
> > > Oh, sorry, I meant we use both MACs on Zynq, however the PHYs are on the MDIO
> > > bus of the first MAC.  So, the second MAC is used for ethernet but not for MDIO,
> > > and so it does not have any PHYs under its DT node.  It would be nice if there
> > > were a way to tell macb not to bother with MDIO for the second MAC, since that's
> > > handled by the first MAC.
> > 
> > Yes, exactly, add support for status = "disabled" in the mdio node.
> 
> Unfortunately, the 'macb' doesn't have a "mdio node", or alternatively:
> the node representing the mdio bus is the same node which represents the
> macb instance itself.  Setting 'status = "disabled"' on this node will
> just prevent the probing of the macb instance.

:-(

It is very common to have an mdio node within the MAC node, for example imx6sx-sdb.dtsi

&fec1 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_enet1>;
        phy-supply = <&reg_enet_3v3>;
        phy-mode = "rgmii";
        phy-handle = <&ethphy1>;
        status = "okay";

        mdio {
                #address-cells = <1>;
                #size-cells = <0>;

                ethphy1: ethernet-phy@1 {
                        reg = <1>;
                };

                ethphy2: ethernet-phy@2 {
                        reg = <2>;
                };
        };
};

&fec2 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_enet2>;
        phy-mode = "rgmii";
        phy-handle = <&ethphy2>;
        status = "okay";
};

This even has the two phys on one bus, as you described...

     Andrew