I want to turn UART2 RTS to GPIO OUT and CTS to GPIO IN.
I changed pinmux .cfg, so that UART2 RTS and CTS are GPIO. I also found out that UART2 RTS maps to GPIO (X,6) and CTS maps to GPIO (X, 7).
I connect RTS pin with CTS pin in hardware (loopback).
I could get it to work under Linux. I tested using /sys/class/gpio/export under Linux. When I drive GPIO for RTS to 1/0, I can get 1/0 from GPIO for CTS correspondingly.
But I couldn’t get it to work under cboot.
cboot provide tegra-gpio driver support. So it is easy to read/write GPIO in cboot. I am confident with my code in cboot.
This is what I change in pinmux .cfg:
pinmux.0x0243d080 = 0x00000001; # uart2_rts_px6: rsvd1, tristate-disable, input-disable, lpdr-disable
pinmux.0x0243d088 = 0x00000059; # uart2_cts_px7: rsvd1, pull-up, tristate-enable, input-enable, lpdr-disable
I didn’t chang dtb for Linux or cboot. I don’t think I need.
Is there anything that I am missing? Why it works under Linux, but not work under cboot?