Re: powerpc, fs_enet: scanning PHY after Linux is up

On Wed, Oct 6, 2010 at 7:50 AM, Holger brunck [off-list ref] w=
rote:

Hello Heiko,

On 10/06/2010 11:53 AM, Heiko Schocher wrote:

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So, the question is, is there a possibility to solve this problem?

If there is no standard option, what would be with adding a
"scan_phy" file in

/proc/device-tree/soc\@f0000000/cpm\@119c0/mdio\@10d40
(or better destination?)

which with we could rescan a PHY with
"echo addr > /proc/device-tree/soc\@f0000000/cpm\@119c0/mdio\@10d40/sc=

an_phy"

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(so there is no need for using of_find_node_by_path(), as we should
=A0have the associated device node here, and can step through the chil=

d

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=A0nodes with "for_each_child_of_node(np, child)" and check if reg =3D=

=3D addr)

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or shouldn;t be at least, if the phy couldn;t be found when opening
the port, retrigger a scanning, if the phy now is accessible?

One option would be to still register a phy_device for each phy
described in the device tree, but defer binding a driver to each phy
that doesn't respond. =A0Then at of_phy_find_device() time, if it

Maybe I din;t get the trick, but the problem is, that
you can;t register a phy_device in drivers/of/of_mdio.c
of_mdiobus_register(), if the phy didn;t respond with the
phy_id ... and of_phy_find_device() is not (yet) used in fs_enet

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matches with a phy_device that isn't bound to a driver yet, then
re-trigger the binding operation. =A0At which point the phy id can be
probed and the correct driver can be chosen. =A0If binding succeeds,
then return the phy_device handle. =A0If not, then fail as it currently
does.

Wouldn;t it be good, just if we need a PHY (on calling fs_enet_open)
to look if there is one?

Something like that (not tested):

in drivers/net/fs_enet/fs_enet-main.c in fs_init_phy()
called from fs_enet_open():

Do first:
phydev =3D =A0of_phy_find_device(fep->fpi->phy_node);

Look if there is a driver (phy_dev->drv =3D=3D NULL ?)

If not, call new function
of_mdiobus_register_phy(mii_bus, fep->fpi->phy_node)
see below patch for it.

If this succeeds, all is OK, and we can use this phy,
else ethernet not work.

!!just no idea, how to get mii_bus pointer ...

in my understanding it should be posssible to get this pointer via the pa=

rent of

the device_node you got via the private data of the fs_enet:
fep->fpi->phy_node->parent should point you to the device_node for the md=

io_bus.

Yes, this will give you the mdio bus node pointer.

In the next step you should be able to get the pointer of of_device for t=

he

mdio_bus:
ofdevice* ofdev =3D to_of_device(fep->fpi->phy_node->parent);

of_device is just an alias for platform_device now, and not all mdio
busses will be instantiated by a platform device.  This method won't
always work.  What is really needed is the pointer to the mii_bus
structure.  That can be obtained by looping over the members of the
mdio_bus_class and comparing the mii_bus->device.parent->of_node to
the parent node from above.

g.