Troubleshooting • Setting pin alt value using gpio in config.txt RPi5

If I set GPIO 10 to a3 using pinctrl it works

barrie@albert:~$ pinctrl set 10 a3
barrie@albert:~$ pinctrl get 10
10: a3 pd | lo // GPIO10 = SDA1

However, if I do this in config.txt

barrie@albert:~$ tail -1 /boot/firmware/config.txt
gpio=10=a3

and reboot the change has not been applied

barrie@albert:~$ sudo reboot
The system will reboot now!
...
barrie@albert:~$ pinctrl get 10
10: ip pd | lo // GPIO10 = input

I can make other changes to GPIO 10 in config.txt, for example setting it to pull up.

barrie@albert:~$ tail -2 /boot/firmware/config.txt
gpio=10=pu
gpio=10=a3
(reboot)
barrie@albert:~$ pinctrl get 10
10: ip pu | hi // GPIO10 = input

Does anyone know why this is not working? It looks like there may be some undocumented restrictions in what you can do with gpio in config.txt

Statistics: Posted by ruralgeek — Sat Jan 25, 2025 2:06 am

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