shaddow501 Posted June 12, 2019 Posted June 12, 2019 Hello Does anyone know how to toggle GPIO output at boot / power up as an overlay or similar? I have seen only examples that show GPIO in function and I didnt find much information how to toggle GPIO out function. Basically I would like to be able to turn LCD back light on when the board is booting and than to be able to control the brightness. (That I can do after the Linux is up and running) but before the Linux is up I still want to be able to control the LCD back light. Can anyone help with that matter?
nradulovic Posted June 13, 2019 Posted June 13, 2019 Hello, Did you have a look at this? https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt There are some attributes that can set initial value during initialization. See for example: output-low and output-high properties. Is that what you need?
shaddow501 Posted June 14, 2019 Author Posted June 14, 2019 On 6/13/2019 at 10:17 AM, nradulovic said: Hello, Did you have a look at this? https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt There are some attributes that can set initial value during initialization. See for example: output-low and output-high properties. Is that what you need? Actually I need to see a working example of the dts file... Because I do not know how to build it correctly.
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