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Message-ID: <CAAtXAHe_fX9_XExvFj20a0L-=b0Z1gX410=wnR=P2DjO-hEByA@mail.gmail.com> Date: Thu, 30 Aug 2018 10:21:03 -0700 From: Moritz Fischer <moritz.fischer@...us.com> To: Andrew Lunn <andrew@...n.ch> Cc: "David S. Miller" <davem@...emloft.net>, Kees Cook <keescook@...omium.org>, Florian Fainelli <f.fainelli@...il.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org, Alex Williams <alex.williams@...com> Subject: Re: [PATCH net-next 1/3] net: nixge: Add support for fixed-link subnodes Hi Andrew, On Wed, Aug 29, 2018 at 8:04 PM, Andrew Lunn <andrew@...n.ch> wrote: > On Wed, Aug 29, 2018 at 05:40:44PM -0700, Moritz Fischer wrote: >> Add support for fixed-link cases where no MDIO is >> actually required to run the device. >> In that case no MDIO bus is instantiated since the >> actual registers are not available in hardware. > > Hi Moritz > > There are a few different use cases here: > > The hardware is missing MDIO - You need fixed-link. Agreed. > > The hardware has MDIO, but you don't have a PHY connected on it, and > use fixed link. Since it's an FPGA design in that case we'd probably build the hardware without MDIO to save resources. > The hardware has MDIO, and it is used e.g. for an Ethernet switch, or > a PHY for another Ethernet interface. Plus you need fixed link. We haven't had that yet but I can see that happen. > > The binding typically looks like: > > &fec1 { > phy-mode = "rmii"; > pinctrl-names = "default"; > pinctrl-0 = <&pinctrl_fec1>; > status = "okay"; > > fixed-link { > speed = <100>; > full-duplex; > }; > > mdio1: mdio { > #address-cells = <1>; > #size-cells = <0>; > status = "okay"; > > switch0: switch0@0 { > compatible = "marvell,mv88e6085"; > pinctrl-names = "default"; > pinctrl-0 = <&pinctrl_switch>; > reg = <0>; > eeprom-length = <512>; > interrupt-parent = <&gpio3>; > > It is important you have the mdio subnode, with PHYs and switches as > children. The driver currently gets this wrong, it uses > pdev->dev.of_node. Oh, whoops. Yeah I should look into that. Any good examples of drivers doing it right? Is the one going with the DT snippet above a good example? > > So the first patch should be to extend this behaviour. Look for a > child node called mdio. If it exists, call nixge_mdio_setup() passing > that child. Otherwise continue using pdev->dev.of_node, so you don't > break backwards compatibility. Ok will do. > > Then a patch adding support for fixed-link. If the mdio child node > exists, you still need to register the MDIO bus. If there is no child > node, but there is a fixed-link, skip registering the mdio bus with > pdev->dev.of_node. > > Andrew Thanks for your feedback, much appreciated! Moritz
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