Re: [PATCH] net: emaclite: adding MDIO and phy lib support

[Grant Likely <grant.likely@secretlab.ca>]

On Fri, Feb 5, 2010 at 10:50 AM, John Linn <John.Linn@xilinx.com> wrote:
>> -----Original Message-----
>> From: Grant Likely
>> Sent: Thurs, 4 Feb 2010 11:12:29 AM
>> To: John Linn
>> Subject: FW: [PATCH] net: emaclite: adding MDIO and phy lib support
>>
>> Hi John and Sadanand. =A0Looks like a good patch, but a few issues to
>> resolve. =A0Comments below.
>>
>> g.
>
> Somehow I didn't get this message but found it out on the web, so this
> is a contrived version of the message so I could respond :)
>
>>
>> On Wed, Feb 3, 2010 at 5:49 PM, John Linn <john.linn@xxxxxxxxxx>
> wrote:
>> > These changes add MDIO and phy lib support to the driver as the
>> > IP core now supports the MDIO bus.
>> >
>> > The MDIO bus and phy are added as a child to the emaclite in the
> device
>> > tree as illustrated below.
>> >
>> > mdio {
>> > =A0 =A0 =A0 =A0#address-cells =3D <1>;
>> > =A0 =A0 =A0 =A0#size-cells =3D <0>;
>> > =A0 =A0 =A0 =A0phy0: phy@7 {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0reg =3D <7>;
>>
>> For completeness, phy node need a "compatible" property.
>
> It seems like this is in the device tree only but the driver won't use
> it. So no real affect on the driver unless I'm not synced up with you.

That's right.  That's why I said "for completeness".  This is just an
example phy node, but it is good practice to give accurate examples.
:-)

>> > =A0 =A0 =A0 =A0/* Set the MAC address in the EmacLite device */
>> > - =A0 =A0 =A0 xemaclite_set_mac_address(lp, ndev->dev_addr);
>> > + =A0 =A0 =A0 xemaclite_update_address(lp, ndev->dev_addr);
>> > +
>> > + =A0 =A0 =A0 /* Check if MDIO is included in the HW */
>> > + =A0 =A0 =A0 lp->has_mdio =3D get_bool(ofdev, "xlnx,include-mdio");
>> > + =A0 =A0 =A0 if (lp->has_mdio) {
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 lp->phy_node =3D of_parse_phandle(ofdev-=
>node,
> "phy-handle", 0);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rc =3D xemaclite_mdio_setup(lp, &ofdev->=
dev);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (rc)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_warn(&ofdev->dev, "e=
rror registering
> MDIO bus\n");
>> > + =A0 =A0 =A0 }
>>
>> What if the phy is attached to a different MDIO bus (which is
>> completely possible)? =A0The fetching of phy_node should be performed
>> regardless of whether or not xlnx,include-mdio is set.
>>
>
> So the issue here is that the IP core can be built without any PHY
> interface and MDIO bus.

Right, but just because the *core* doesn't have a phy interface built
in, doesn't mean that the PHY isn't attached to a different MDIO bus
(ie. on another emaclite, or on a gpio driven MDIO bus).  So even if
mdio is configured out, the driver should still handle the case of it
having an valid phy-handle.

g.

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.