Request for Mesa 5i23_7i48_7i52 firmware

Is there any more to that than adding the line:

setp [HMOT](CARD0).gpio.024.out false

to my halfile? looking at Hostmot2 doc page, it doesn't look like it has to be explicitly added as a gpio in the loadrt hm2_pci config="...etc"

but I'm not sure what else might be required. I've just tried the above setp line, ending it either 'true' or 'false', and still have no activity on P3 pins

You need to set the pin to output mode.
(all GPIO start-up as input pins)

setp [HMOT](CARD0).gpio.024.is_output true
setp [HMOT](CARD0).gpio.024.out false