(Note: This is specific to PPC405EP but it might be applicable to other 4xx cpus)
On a PPC405EP based boards, U-Boot is initializing below registers to select between primary and alternate functions of the GPIO pins (e.g. GPIO10 vs CS1) using the CFG_CPIO0_... macros defined in the board config file.
GPIO0_TCR, GPIO0_OSRH, GPIO0_OSRL, GPIO0_TSRH, GPIO0_TSRL, GPIO0_ISR1H, GPIO0_ ISR1L
This much is sufficient for alternate function programming. However, if a the GPIO pin is actually used as GPIO output pin, the initial signal level presented happens to be "0" which may not be appropriate for some implementations.
I propose to introduce CFG_GPIO0_OR and CFG_CPIO0_ODR macros that could be defined in the appropriate board config file and initialize GPIO0_OR and GPIO0_ODR before GPIO0_TCR. If these macros are undefined the existing code behavior could be maintained so the additional macros would not break any existing board or add any additional code.
I will be introducing a patch to take care of this but I wanted to get feedback first.
FYI: For our board, we have a GPIO line connected to an active low reset line of a custom ASIC chip. There is a pull-up so during the time while this pin is tri-state/input we should not reset the ASIC automatically while management processor is booting. Our ASIC can operate independently while the management processor is booting.