Hi,
I’m using Jetson Orin AGX devkit’s pin8 of the expansion header as a gpio out controlling external devices. I have no problem controlling it using gpioset gpiofind "PR.02"=1, it works great.
Only problem: when I boot the Jetson, this pin8 immediately is driven up by the bootloader. I have to wait until userspace is up before I can take it down again.
Can I change that? configure the bootloader not to drive that pin up?
Thanks!
*** Please note that this reply is generated by LLM automatically ***
The issue you’re facing is related to the Bootloader Implementation, specifically the Bootloader Scratch Register and Partition Settings.
When the Jetson AGX Orin devkit boots, the bootloader initializes the GPIO pins, including pin8 of the expansion header, which is being driven up. This is a default behavior of the bootloader.
To change this behavior, you can try modifying the Bootloader Implementation. One possible solution is to update the Bootloader Scratch Register, which is responsible for storing the GPIO configuration. However, this requires a deep understanding of the bootloader’s inner workings and may not be a straightforward process.
Another approach is to modify the Partition Settings, which control how the bootloader initializes the GPIO pins. You can try updating the Partition Settings to exclude pin8 from being driven up during boot.
To do this, you’ll need to use the Bootloader Tools, specifically the Boot Control tool. You can use Boot Control to modify the bootloader’s configuration and update the Partition Settings.
Here’s a step-by-step guide to help you get started:
bootctl command to update the Partition Settings.Keep in mind that modifying the bootloader’s configuration can be complex and may require a good understanding of the underlying hardware and software. Be cautious when making changes, as they can potentially brick your device.
If you’re not comfortable with modifying the bootloader’s configuration, you can also consider using a workaround, such as using a GPIO expander or an external circuit to control the pin8 signal.
In comparison to other issues related to the Jetson AGX Orin, such as the AGX Orin GPIO issue, this problem is specific to the bootloader’s initialization of GPIO pins. The AGX Orin GPIO issue is related to a kernel problem causing GPIO pin request problems, whereas your issue is related to the bootloader’s configuration.
I hope this helps you resolve the issue. If you have further questions or need more guidance, feel free to ask!
Hi bardavid52,
What’s the Jetpack version in use?
pinmux/gpio dtsi are loaded in early boot(MB1).
Please just configure them in pinmux spreadsheet as GPIO/Output/Drive 0 if you want it to be default low.
Here’s Jetson Linux Developer Guide docs that show how to make PR.02 change in the bootloader.
Or you could try below but for me the jetson-io.py is non intuitive.
sudo /opt/nvidia/jetson-io/jetson-io.py
I’m using 36.4.3.
The signal is clearly asserted by the bootloader - as soon as power is applied to the Jetson - and much much earlier before the kernel even boots.
Do you mean that if I change the kernel’s dtsi then it is loaded to the bootloader as well? usually the bootloader and the kernel have two different (albeit similar) device tree files, and updating the kernel’s dtsi does not affect the bootloader’s behavior.
Thank you. Yeah I’m not sure that jetson-io.py can be used to control individual pinmux to gpio settings. probably only functional groups like can, etc..