Bootloader pulling GPIO pins high

[ToradexAI]

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

Did you like my answer?

---

Hello,

Thank you for reaching out with your question. The behavior you’re observing, where GPIO pins are pulled high during the bootloader phase, is likely due to the default configuration of the bootloader, which can set GPIO states before the Linux kernel takes over. This is a common issue when the bootloader initializes hardware differently than the final operating system configuration.

To address this, you can modify the U-Boot bootloader configuration to ensure that the GPIO pins are set to the desired state during the boot process. Here are some steps you can take:

1. Check U-Boot Configuration:

   • Access the U-Boot source code for your Colibri iMX8X module, typically available in the Toradex BSP (Board Support Package).
   • Locate the board-specific configuration files, which might be under a directory like board/toradex/colibri_imx8x/.

2. Modify GPIO Initialization:

   • In the U-Boot source, look for the GPIO initialization code, often found in board-specific files or common initialization routines.
   • Ensure that the GPIO pins in question are configured as pull-downs during the bootloader phase. You may need to add or modify code to explicitly set these pins to the desired state.

3. Rebuild U-Boot:

   • After making the necessary changes, rebuild the U-Boot bootloader. Follow the Toradex documentation for building and deploying U-Boot to your module.

4. Test the Changes:

   • Flash the modified U-Boot to your module and observe the GPIO behavior during boot. Verify that the pins remain in the pull-down state as expected.

By ensuring that the bootloader configures the GPIO pins correctly, you can prevent them from being pulled high during the boot process. If you continue to experience issues, double-check the device tree and U-Boot configurations to ensure consistency across all stages of the boot process.

I hope this helps resolve your issue. If you have any further questions, feel free to ask.

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

GPIO handling in uboot

Hi, I am working with a vf61 and wanted to set the GPIO at boot time by uboot. What I can do is setting, clearing, toogling of the gpios in uboot. However, saving Information to Flash does not work as expected. I used the example shown here: How can I save the gpio startup setting to the Environment? Thanks and best regards - Tom Bootloader: Colibri VFxx # version U-Boot 2015.04+fslc+gb66337d (Dec 30 2015 - 16:11:51) arm-angstrom-linux-gnueabi-gcc (Linaro GCC 4.9-2015.03) 4.9.3 2015031…

Hardware Revision Detection using GPIO Inputs in U-Boot

Hi, We’re currently migrating from WinCE to Linux, using Toradex’ provided BSPs based on Yocto. My current test module is a Colibri IMX8QXP 2GB (No Wifi), existing module is the Colibri T30. For now, all the development and testing takes place on the IMX8 module (Using BSP 5.7), but keep in mind that at a later time the existing T30 should be ported from CE to Linux as well (BSP 2.8). It’s preferable to keep the changes between the two images as small as possible (That’s why device tree overl…

Verdin iMX8M - Device Tree Overlay, GPIO Output, Default State.