GPIO JP6.1 different behavior than JP5.1.2

[KevinFFF]

Hi enc0der,

@enc0der

Can someone explain what is broken in JP6.1?

To control GPIO in JP6.x manually, you have to apply the following patch.
40hdr - SPI1 gpio padctl register bit[10] effect by gpiod tools in JP6 - #20 by KevinFFF
We found gpiod command would set bit10 causing it configured as SFIO instead of GPIO.

@enc0der

Next, if we change the pin_mux spreadsheet, will the GPIO work then as they had in the past?

Yes, GPIO can work as expected if you’ve configured it correctly.
Please just note that sysfs method to control GPIO has deprecated in JP6.x. We would suggest using gpiod instead.

@enc0der

Last question. Given we are running on an SSD that is full of dev setup, can someone point us to the steps for just updating the pin_mux settings? Right now we are using an FDT with an OVERLAYS, so we don’t want to break all that. Is there a flash command we can run that will JUST update the pin_mux settings?

Please note that pinmux/gpio dtsi are loaded in early boot(MB1) rather than kernel. It is not relating to the one your specified in FDT/OVERLAY entry in extlinux.conf.
As a result, you have to reflash the board to apply the change.

If you do not want to reflash the board, there’s a tegra-pinctrl driver can help to reconfigure the pinmux in kernel. (it is also how jetson-io works). You can try to add related configuration in kernel device tree for your use case.