If RK pin is RK_out and they go to AFG_in pins, that might suggest the RK is configuring the AFG using five 1bit words, or maybe one 5bit word. Not sure how the functionality is. Maybe a 5bit word is a scaling factor from 1 to 32*16*8*4*2 ?
another possibility is those 5 pins are connected to FPGA to tell FPGA what to do to output to AFG, not directly to AFG module.
If an 800 series runs as a 900, do you get an AFG freq panel to punch in a freq? Sure, it won't do anything but you can monitor the gpio pins to see if there's any relevance.
i spent a fair amount of time doing this, you can see in attachments earlier. but anything in between my finger press on GUI and those exposed interface pins are a black box to me, in other word i dont know. so i dont want to speculate one of many possibilities. but based on souldevelop's report, those 5 pins are configured as output, so i have a doubt those 5 pins checking are responsible to detect AFG presence or not and cause the dso to hang. thats the matter of discussion right now imho. whatever those 5 pins do, as long as its not for status checking (AFG presence), is not my concern atm. ymmv.
ps: for the past few many hours, i tried to install everything (android studio, apktool, jadx decompiler, bluestacks) to look for what the FW does, where the FW calls to the afg_gpio.ko but not yet success, all i see are bunch of java import and export nonsense stuffs