I need access to both 1.8V and 3.3V for a level shifter so that I can get the Jetson to communication with a pixhawk autopilot via the Jetson UART2. Looking here: http://elinux.org/Jetson/GPIO, it mentions that 3.3v is available on J3A1 pins 16 and 22. If you go further down to the complete pin list, it appears pin 10 also has 3.3v and is labelled 3.3V_RUN_TOUCH. What does that mean? Is there a reason that pin could not / should not be used?
The signal names represent NVIDIA recommended uses for the signals, but are free to use. The intent is that if a designer is going to add a feature to a Tegra K1, they use the designated signal name. In that way, every TK1 design would use the same signal for a give feature. For example, Pin 27 | EN_VDD_BL | DAP3_DOUT is a backlight supply enable. If you are adding a display that has a backlight, you should use that signal.
With that said, the usage is a suggestion. The pins are available as you please.