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

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Message-ID: <572298D2.3060809@gmail.com>
Date:	Thu, 28 Apr 2016 16:12:18 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Andrew Lunn <andrew@...n.ch>
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 28/04/16 15:12, Andrew Lunn wrote:
> 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?

Fair enough, I will submit something after re-spining this patch to use
-ENODEV, which I agree is a better return code. Did you want me to
remove that blurb from the commit message?
-- 
Florian