I've done a little more work on this. I've been able to swap the UART pins around to a certain extent, but it's still being stubborn. I've been able to move the console output from the main UART from GPIO14 to GPIO32. I've somehow also managed to get the main UART to output to both GPIO32 and GPIO14 simultaneously (although it wouldn't RX anything when that was happening)! However I still can't get it to simply move the console over to using the mini-UART.
I've worked out that the serial port seems to be selected by the status of the pin multiplexers. It checks to see whether GPIO15 is multiplexed to the main port. If not, it checks to see whether GPIO15 is multiplexed to the alternate port. I tried forcing it to think that the secondary UART was multiplexed by forcing a return value in the is_serial_muxed() functions to be false for the main UART and true for the mini-UART, however it just gives me a rainbow splash screen of death.
Can I have some pointers as to how I debug what's causing the Pi to fail to boot when I try forcing the mini-UART? Clearly something is wrong and causing it to fail. Will it output anything over the early debug UART and, if so, what values do I need to put into the config for that to work? I tried adding the register addresses I found in the datasheet, however I couldn't get anything out of it.
Kindest regards, Ed
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