How do I not enable a GPIO pin on boot up?

[JamesQ 0]

Hi,

 

I'm trying to solve a problem here. I have a Pine64so board with LTE module plugged into the USB and a battery back up. With the battery drained to 0%, the board will not boot up with the LTE module plugged into the USB port even with a microUSB power supply, because LTE is drawing too much power. But with the battery slightly charged or the LTE module unplugged it boots up just fine. I know that USB power is enabled by the u-boot, because with the Armbian SD card ejected, when I plug in the microUSB power supply, the board doesn't automatically provide power to the USB port, and the battery charges by default. So I'm trying to figure out where in the uboot code, it turns on the GPIO that controls the USB power. I assume it's really early in the code, because when it doesn't boot, I only see the prompt (via UART) "Trying to boot from MMC1" before it shuts down.

 

Thanks to the help.

 

James