Jetson Nano u-boot GPIO using

Good afternoon, dear Nvidia! Please, tell me how can I control GPIO 4 from U-BOOT in Jetson Nano? In different files all of JN’s GPIO has different names and I cannot understand what name should I use?
There is Red LED on this GPIO and I should turn it on if my POST test failed.
By the means of GPIO 4 I meant:

Any specific reason you have to do it in U-Boot instead of Linux?

Yes - I showing to my students how to do any verification in U-BOOT. Usually there is something like U-BOOT reference manual document that explains to you how to work with simple interfaces on target board, but I couldn’t find any information about how can I use GPIO in U-BOOT on Jetson Nano.

No one do verification after boot. In bad cases - you couldn’t boot because of any errors - then you should start POST test in BIOS or another system loader. Every device has some POST during each boot.

I don’t think we support such use cases.
GPIO is not related to booting in any aspect.

Evey board that I used could work with GPIO and I sure that JN is able too. I only don’t know what is the pins naming for the exact U-BOOT.
Simple if board is not booting in Linux - I can turn on exact LED to understand what device or interface should I blame for this.

Sorry that I miss it.
You can actually do:
https://docs.u-boot.org/en/latest/usage/cmd/gpio.html
For GPIO numbering, refer to:

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