You are experienced builder of complex systems, had time to build test that generates long test vectors and looks for any corruption, but had no time to check rPI I/O pin specification. Right.
It didn't appear to you that just
maybe there was an actual reason why I needed to build the communication between the STM32 and the Raspberry, and there might be
other reasons I needed to test the reliability of the complete chain (using generated test data instead of actual production point cloud data) - including software timing, and to analyze the Raspberry's CPU load - and just
maybe I happened to have a few extra minutes so that I played around with the speed setting as well, just for fun. For production, we are using the highest speed setting IIRC. My "measurement" was not needed to determine this.
You know, maybe I didn't do my "test" just to entertain you on the forum? Maybe it was a side result of something more meaningful? Just maybe?
Guess what? Raspberry Pi GPIO is not properly specified. So the reason I did "not look up" the spec is that it doesn't exist. The GPIO header hasn't signal integrity thought out too well. Raspberry Pi is a toy you just end up using. If you need to work with it, you'll get very practical about things.
Again - I encourage you to just ignore any information you don't find useful. I prefer having any publicly available datapoints in discussions instead of completely empty babble, but you need to understand what they mean. Not every piece of information is a scientific gem in itself. I find "ballpark pointers" highly useful, and will be supplying them in the future as well, some better, some worse. Deal with it
.
About the complexity? The board has 14 impedance controlled and length matched parallel buses of 12 bits each, over 4000 vias, 500-watt software-controlled multiphase switch mode converters, BLDC drivers, MEMS sensors, etc. Getting it all routed in 6 layers only was a demanding task, and 35000 lines of code exists at the moment. For a one-man quickie in less than a year total, once you work with this kind of task, you stop worrying about whether your report of IO speed setting on a casual forum discussion is scientifically sound and complete.
Bullshit or not? You decide, and you are free to think whatever you want to. I'm not interested.