I am using GPIO(CON3) pins 8 and 10 for a project. In BPI M1+, functions for those pins are PH0 and PH1 respectively.

https://bananapi.gitbooks.io/bpi-m1-bpi-m1-plus-/content/en/bpi-m1+_gpio_pin_define.html

 

But, when I added overlays=uart3 ,I didn't work properly . When I checked the overlay file sun7i-a20-uart3.dtbo , by changing it to .dts , I figured out that this overlay file uses PG6,PG7 pins, not PH0,PH1  pins.

So, to modify the configurations without adding uart3 overlay in the /boot/armbianEnv.txt file, I wanted to edit the /boot/dtb/sun7i-a20-bananapi-m1-plus.dtb file.

When I check the file, there are uart3_pins_a option and uart3_pins _b in the __symbols section with the path name as below.

Also pins assigned for each pins_a and pins_b are mentiond in the pinctrl@01c20800.

 How can I activate(set) the uart3_pins_b option which is assigned to the correct pins (PH1 and PH0)for BPI M1+ ?

12 hours ago, sunzone said:

 How can I activate(set) the uart3_pins_b option which is assigned to the correct pins (PH1 and PH0)for BPI M1+ ?

Currently this is not implemented, will be added in the future. You should be able to write a custom overlay to change the pinmux variant.