FTDI once again updated their firmware, this time to 1.4.2. The release notes are promising. My goal for today is to try and validate as many of the fixes as I can. If enough of the regressions are fixed, the intended fix to USB host polling rates would actually make my device playable!
The 1.4.2 release did manage to fix the most glaring of bugs, most of the crashers and obvious incorrect behavior is now resolved: Issues Page. Even some of the bigger ones appeared to have progress made, specifically, the USB host polling rate problem. It did now appear that the host driver polled at 8ms for my device which requested a 10ms poll rate.
That was the upside. The downside was that for some reason the device only responded to every 3 out of 4 poll requests for data. (On my linux host, which also polls at 8ms, it responds to every single one). Additionally, something got broken about enumeration for devices which are connected at powerup that made enumeration moderately unreliable. That is a little bit ironic, given that I never had any problems with this before, and the release notes indicate that problems related to this were fixed in 1.4.2.
At this point, I’ve decided against freshening up my scope USB decoding skills again to see what the VNC2 library is doing wrong during enumeration or during the 1/4 interrupt IN polls that nothing comes in. Besides, rock band isn’t as popular as it was 8 months ago anyways. On to other projects, and maybe in a couple more years the VNC2 firmware will be usable enough to revisit.