netdev - Re: [PATCH net-next] of: of_mdio: Check if MDIO bus controller is available

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Message-ID: <20160428221211.GE12753@lunn.ch>
Date:	Fri, 29 Apr 2016 00:12:11 +0200
From:	Andrew Lunn <andrew@...n.ch>
To:	Florian Fainelli <f.fainelli@...il.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	nathan.sullivan@...com, nicolas.ferre@...el.com,
	Rob Herring <robh+dt@...nel.org>,
	Frank Rowand <frowand.list@...il.com>,
	Grant Likely <grant.likely@...aro.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
	<devicetree@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] of: of_mdio: Check if MDIO bus controller is
 available

On Thu, Apr 28, 2016 at 02:55:10PM -0700, Florian Fainelli wrote:
> Add a check whether the 'struct device_node' pointer passed to
> of_mdiobus_register() is an available (aka enabled) node in the Device
> Tree.
> 
> Rationale for doing this are cases where an Ethernet MAC provides a MDIO
> bus controller and node, and an additional Ethernet MAC might be
> connecting its PHY/switches to that first MDIO bus controller, while
> still embedding one internally which is therefore marked as "disabled".
> 
> Instead of sprinkling checks like these in callers of
> of_mdiobus_register(), do this in a central location.

I think this discussion has shown there is no documented best
practices for MDIO bus drivers and how PHYs nodes are placed within
device tree. Maybe you could document the generic MDIO binding, both
as integrated into a MAC device node, and as a separate device?

	   Andrew