• Fabio Estevam's avatar
    ARM: dts: imx6ul-14x14-evk: Enable the GPIO expander · 70f04e9a
    Fabio Estevam authored
    Currently the 74LV595PW GPIO expander is not functional because its OE
    pin is not driven low.
    
    Make it funcional by passing the 'enable-gpios' property inside the
    GPIO expander node.
    
    After putting the OE pin in low state, the outputs of the 74LV595PW all
    go low.
    
    The two KSZ8081 Ethernet PHYs reset lines are driven from the
    the GPIO expander and as they remain low, this causes the Ethernet
    PHYs not to be detected.
    
    There is one solution to this problem as suggested by Andrew Lunn:
    
    "Some devices will respond to MDIO while held in reset, some don't.
    If your PHYs don't you need to add a compatible of the form
    ethernet-phy-id[a-f0-9]{4}\\.[a-f0-9]{4}$ with the PHY ID. The PHY
    will then be probed, independent of if it can be found on the bus or
    not, and that probing will enable the GPIO."
    
    So pass the "ethernet-phy-id0022.1560" for the KSZ8081 PHYs so that they
    both can be functional after 74LV595PW is activated.
    Suggested-by: default avatarAndrew Lunn <andrew@lunn.ch>
    Signed-off-by: default avatarFabio Estevam <festevam@gmail.com>
    Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
    Signed-off-by: default avatarShawn Guo <shawnguo@kernel.org>
    70f04e9a
imx6ul-14x14-evk.dtsi 13.9 KB