Dear Allen Martin,
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Hi Marek, the change to return value here broke serial output on tegra. What I see is that the serial device name (s->name) is "eserial0" as set by serial_ns16550.c, and the name passed in from the stdout environment is "serial" so they don't match and it fails. This always used to be ok because the return code didn't indicate failure and iomux_doenv() would continue on happily, but now it causes iomux_doenv() to fail and no printfs() work after that.
Not sure what the right fix is, should stdout really be set to "eserial0"? It seems "serial" should mean "the default serial device" which for the normal case is the one and only device.
Looking at the source, the obvious course of action is to fix iomux.c .
-Allen
Best regards, Marek Vasut