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DSA has multiple ways of specifying a MAC connection to an internal PHY.
One requires a DT description like this:
port@0 {
reg = <0>;
phy-handle = <&internal_phy>;
phy-mode = "internal";
};
(which is IMO the recommended approach, as it is the clearest
description)
but it is also possible to leave the specification as just:
port@0 {
reg = <0>;
}
and if the driver implements ds->ops->phy_read and ds->ops->phy_write,
the DSA framework "knows" it should create a ds->slave_mii_bus, and it
should connect to a non-OF-based internal PHY on this MDIO bus, at an
MDIO address equal to the port address.
There is also an intermediary way of describing things:
port@0 {
reg = <0>;
phy-handle = <&internal_phy>;
};
In case 2, DSA calls phylink_connect_phy() and in case 3, it calls
phylink_of_phy_connect(). In both cases, phylink_create() has been
called with a phy_interface_t of PHY_INTERFACE_MODE_NA, and in both
cases, PHY_INTERFACE_MODE_NA is translated into phy->interface.
It is important to note that phy_device_create() initializes
dev->interface = PHY_INTERFACE_MODE_GMII, and so, when we use
phylink_create(PHY_INTERFACE_MODE_NA), no one will override this, and we
will end up with a PHY_INTERFACE_MODE_GMII interface inherited from the
PHY.
All this means that in order to maintain compatibility with device tree
blobs where the phy-mode property is missing, we need to allow the
"gmii" phy-mode and treat it as "internal".
Fixes: 2c709e0bda ("net: dsa: microchip: ksz8795: add phylink support")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216320
Reported-by: Craig McQueen <craig@mcqueen.id.au>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Tested-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Link: https://lore.kernel.org/r/20220818143250.2797111-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.