Describe the bug

I set enable_uart=1 in /boot/config.txt to enable access to a serial console on GPIO14+15. This works perfectly fine. However, the kernel sees those GPIOs still as "unused", even though they are actively used by the UART:

$ lsgpio -n gpiochip0
GPIO chip: gpiochip0, "pinctrl-bcm2711", 58 GPIO lines
[...]
        line 14: "GPIO14" unused [input]
        line 15: "GPIO15" unused [input]

This means that I can execute something like gpioset GPIO15=low and break UART functionality. I would rather expect gpioset to complain gpioset: unable to request lines on chip '/dev/gpiochip0': Device or resource busy as it does for other GPIOs when they are already in use (e.g. when using dtoverlay=gpio-shutdown,gpio_pin=26 and trying to execute gpioset GPIO26=low).

Steps to reproduce the behaviour

1. Set enable_uart=1 in /boot/config.txt and reboot
2. Run gpioset GPIO15=low
3. Observe that the command succeeds unexpectedly and UART functionality is now broken

Device (s)

Raspberry Pi 3 Mod. B+, Raspberry Pi 4 Mod. B

System

Arch Linux ARM

$ vcgencmd version
May 14 2025 12:23:36
Copyright (c) 2012 Broadcom
version 17084b403fb60475b8ee2641c26049a7d54bf153 (clean) (release) (start)

$ uname -a
Linux rpi 6.12.43-1-rpi #1 SMP PREEMPT Tue Aug 26 13:22:07 MDT 2025 aarch64 GNU/Linux

Logs

No response

Additional context

No response