[Open-graphics] Initial thoughts

[Timothy Miller]

Erik Schmidt wrote:
> I don't see why TS would want to lock down part of the FPGA design.  The 
> driver could just push out the entire design to the FPGA.  This would be 
> needed for upgrades as development progresses anyways.

First, realise that the host interface and other logic that you would be 
using to reprogram the FPGA is IN the FPGA, so in order to reprogram the 
FPGA, you'd have to reprogram the flash (nowhere else appropriate to 
store it) which could take as long as a few seconds.  THEN you would 
need external logic to assist the reprogramming process (a flipflop 
would probably be enough, but we don't want additional external logic). 
  Finally, when you reprogram the FPGA, you lose ALL state information, 
including PCI config space, so your device disappears off the bus 
(although once it's done reloading, you can reprogram it with the same 
information that was in it before, if you store it first).