Date: Fri, 11 Mar 2016 22:35:16 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: David Daney <ddaney.cavm@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>, Robert Richter <rric@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>, netdev@vger.kernel.org,
        David Daney <david.daney@cavium.com>,
        David Daney <ddaney@caviumnetworks.com>, linux-kernel@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>, Kumar Gala <galak@codeaurora.org>,
        Sunil Goutham <sgoutham@cavium.com>,
        Radha Mohan Chintakuntla <rchintakuntla@cavium.com>,
        "David S. Miller" <davem@davemloft.net>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] net: thunderx: Cleanup PHY probing code.
Message-ID: <20160311213516.GE19277@lunn.ch>
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 <1457714822-5754-2-git-send-email-ddaney.cavm@gmail.com>
 <20160311173125.GI3153@lunn.ch>
 <56E30332.7060003@caviumnetworks.com>
 <20160311180030.GB19277@lunn.ch>
 <56E30DDF.5040506@caviumnetworks.com>
 <20160311190627.GC19277@lunn.ch>
 <56E31E7A.6080905@gmail.com>
 <56E330E4.9090800@gmail.com>
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> For this phy, we have:
> 
>   compatible = "cortina,cs4223-slice";

That actually means something else is happening, i think.

of_mdiobus_register() looks at the children, and decides if each child
is a phy or an mdio device, by calling of_mdiobus_child_is_phy().
Since this compatible string is not in whitelist_phys[], it will
return false. of_mdiobus_register() will then do a
of_mdiobus_register_device(). This compatible means it is an MDIO
device, not a PHY. So when you later call of_phy_find_device() it is
always going to return NULL, because there is no PHY there, only an
MDIO device.

How usable is the hardware without a PHY driver? Is a better solution
that your write a very minimal PHY driver?

     Andrew