Device tree overlay

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GPIO Configuration Issue with Device Tree Overlay

Hello Ivan! I can help you resolve this GPIO configuration issue. Based on the available information sources, there are several key points to address when configuring GPIO outputs using device tree overlays on the Verdin iMX8MP.

Checking Applied Overlays

First, let’s verify that your overlay was applied successfully. You can check if the overlay was applied correctly by examining the device tree properties(1):

# ls /proc/device-tree/chosen/overlays/
# cat /proc/device-tree/chosen/overlays/verdin-imx8mp-frontpanel-leds.dtbo

If the overlay was applied successfully, this should return 0(1).

Common GPIO Configuration Issues

From the community discussions, there are several common issues when configuring GPIOs with device tree overlays on Verdin iMX8MP(2):

  1. Pin Control Configuration: The pin control node must be correctly defined in your overlay with proper pin settings(2).

  2. GPIO Node Structure: The GPIO node should include the gpio-hog property with correct gpios property and output-high or output-low directive(2).

  3. Pin Control Reference: A critical requirement is that the pin control configuration must be properly referenced in the pinctrl-0 property of the iomuxc node(2).

Required Configuration Structure

Based on the community examples, your device tree overlay should include both the pin control configuration and proper referencing(2):

&iomuxc {
    pinctrl-0 = <&pinctrl_gpio1>, <&pinctrl_gpio2>,
                <&pinctrl_gpio3>, <&pinctrl_gpio4>,
                <&pinctrl_gpio7>, <&pinctrl_gpio8>,
                <&pinctrl_gpio_hog2>, <&pinctrl_gpio_hog3>, <&pinctrl_gpio_hog4>,
                <&pinctrl_hdmi_hog>, <&your_custom_pinctrl>;
};

Troubleshooting Steps

  1. Verify Pin Assignments: Check the Verdin iMX8MP datasheet to confirm the correct GPIO mappings for SODIMM 42, 44, and 46.

  2. Check for Conflicts: Ensure there are no conflicting overlays or pre-enabled overlays that might override your GPIO settings(2).

  3. Reboot Process: After making changes to your overlay, ensure you reboot the system properly to apply the overlay correctly(2).

  4. Pin Control Integration: Verify that your custom pin control configuration is properly added to the pinctrl-0 list in the iomuxc node(2).

Without seeing your specific overlay file, the most likely issue is that the pin control configuration isn’t properly referenced in the iomuxc node’s pinctrl-0 property, which is a common requirement for GPIO configuration on the Verdin iMX8MP(2).

Best regards, Toradex AI Assistant.

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