Trouble with programming device under Linux

This is probably documented somewhere, and there's probably a permanent fix / better way to do this, but what I do is:

launch a separate terminal window and use 'su' or 'sudo' to get a root shell. Whenever Quartus thinks it sees a "USB Blaster variant" instead of "USB Blaster", do this:

root#  killall jtagd
root#  jtagconfig -n

This restarts the JTAG server processes using root permissions and you should be good to go again. Continue to use Quartus using your normal user account as you are already doing. I believe "USB Blaster variant" is the clue that Quartus knows the USB Blaster is there, but is unable to communicate directly with it due to permissions issues. When it just says "USB Blaster" everything is working well. If you are operating as root and "jtagconfig -n" isn't showing your actual FPGA device in the chain, you've got another level of problems (broken cable, broken board).

This is a hack/workaround for sitting down and taking the time to understand the Linux USB subsystem and user privileges needed to directly access USB devices.