For a long time the dsa driver has been providing a builtin mdio bus
via dsa default attribute user_mii_bus. This simply uses read/write
commands from the standard realtek otto bus (aka parent). The reason
has always been unclear.
Looking around the kernel 6.18 codebase there is only one case where
this is really needed. The only consumer is dsa_user_phy_setup().
ret = phylink_of_phy_connect(dp->pl, port_dn, phy_flags);
if (ret == -ENODEV && ds->user_mii_bus) {
/* We could not connect to a designated PHY or SFP, so try to
* use the switch internal MDIO bus instead
*/
ret = dsa_user_phy_connect(user_dev, dp->index, phy_flags);
}
Luckily the phylink_of_phy_connect() works fine and the internal bus
access is not needed at all. No need to keep the bus alive. Drop it.
While we are here fix the error handling issue of this code
if (!of_device_is_available(dn))
ret = -ENODEV;
Returncode was set to error but never handed back to the caller.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/22799
Signed-off-by: Robert Marko <robimarko@gmail.com>
ad087c20b8