netdev - RE: [PATCH net-next 1/3] enetc: Add mdio bus driver for the PCIe MDIO endpoint

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Date:   Wed, 24 Jul 2019 09:53:15 +0000
From:   Claudiu Manoil <claudiu.manoil@....com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "David S . Miller" <davem@...emloft.net>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Alexandru Marginean <alexandru.marginean@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Leo Li <leoyang.li@....com>, Rob Herring <robh+dt@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH net-next 1/3] enetc: Add mdio bus driver for the PCIe MDIO
 endpoint

>-----Original Message-----
>From: Andrew Lunn <andrew@...n.ch>
>Sent: Wednesday, July 24, 2019 1:25 AM
>To: Claudiu Manoil <claudiu.manoil@....com>
>Cc: David S . Miller <davem@...emloft.net>; devicetree@...r.kernel.org;
>netdev@...r.kernel.org; Alexandru Marginean
><alexandru.marginean@....com>; linux-kernel@...r.kernel.org; Leo Li
><leoyang.li@....com>; Rob Herring <robh+dt@...nel.org>; linux-arm-
>kernel@...ts.infradead.org
>Subject: Re: [PATCH net-next 1/3] enetc: Add mdio bus driver for the PCIe MDIO
>endpoint
>
>> +	bus = mdiobus_alloc_size(sizeof(u32 *));
>> +	if (!bus)
>> +		return -ENOMEM;
>> +
>
>> +	bus->priv = pci_iomap_range(pdev, 0, ENETC_MDIO_REG_OFFSET, 0);
>
>This got me confused for a while. You allocate space for a u32
>pointer. bus->priv will point to this space. However, you are not
>using this space, you {ab}use the pointer to directly hold the return
>from pci_iomap_range(). This works, but sparse is probably unhappy,
>and you are wasting the space the u32 pointer takes.
>

Thanks Andrew,
This is not what I wanted to do, don't ask me how I got to this, it's
confusing indeed.
What's needed here is mdiobus_alloc() or better, devm_mdiobus_alloc().
I've got to do some cleanup in the local mdio bus probing too.
Will send v2.

Thanks,
Claudiu