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Srinivas Kandagatla authored
This patch adds a basic check in stmmac_mdio_unregister to see if mdio bus registeration for this driver was actually sucessfull or not. Use case here is, if BSP considers using mdio-gpio bus along with stmmac driver by passing mdio_bus_data as NULL in platform data. Call to stmmac_mdio_register with mdio_bus_data as NULL returns 0, which is a considered sucessfull call form stmmac. Then again when we unload the driver we just call stmmac_mdio_unregister, this is were the actual problem is stmmac-mdio code dont really know at this instance of calling that stmmac_mdio_register was actually successful. So Adding a check in stmmac_mdio_unregister is always safe. Without this patch stmmac driver calls stmmac_mdio_register from stmmac_release which Segfaults as mii bus was never registered at the first point. Originally the this bug was found when unloading an stmmac driver instance which uses mdio-gpio for smi access. Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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