Hi Rob,
On Mon, Aug 21, 2017 at 02:10:33PM -0500, Rob Herring wrote:
> On Sun, Aug 20, 2017 at 5:28 AM, Baruch Siach <baruch@xxxxxxxxxx> wrote:
> > Add device-tree binding documentation SFP transceivers. Support for SFP
> > transceivers has been recently introduced (drivers/net/phy/sfp.c).
> >
> > Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
> > ---
> >
> > The SFP driver is on net-next.
[...]
> > +Optional Properties:
> > +
> > +- i2c-bus : phandle of an I2C bus controller for the SFP two wire serial
> > + interface
>
> Why not a child of the i2c bus it is on? IOW, what should this be a child of?
As I understand form the code the ID of the SFP i2c slave is derived from the
Ethernet PHY 'reg' property. The PHY node's 'sfp' property points to a phandle
of the sff,sfp node.
It is also possible for the 'sfp' property to appear directly in the Ethernet
device node.
Quoting RMK from merge commit 234709336b8 (net-next):
To add to the complexity, SFP modules can be connected in at least
two places:
1. Directly to the serdes output of a MAC with no intervening PHY.
For example:
mvneta ----> SFP socket
2. To a PHY, for example:
mvpp2 ---> PHY ---> copper
|
`-----> SFP socket
This code supports both setups, although it's not fully implemented
with scenario (2).
baruch
--
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