[PATCH 2/4] ARM: dts: imx6ul-14x14-evk: Enable the GPIO expander

[Andrew Lunn]

On Thu, Jan 07, 2021 at 08:50:42PM -0300, Fabio Estevam wrote:
> 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: Andrew Lunn <andrew at lunn.ch>
> Signed-off-by: Fabio Estevam <festevam at gmail.com>

Reviewed-by: Andrew Lunn <andrew at lunn.ch>

    Andrew