https://lists.berlios.de/pipermail/openocd-development/2009-August/009939.html

1. It can only be built with the FTD2XX driver. libftdi supports FT2232H/FT4232H 
since version 0.16 

2. A speed value of 0 is used as a RTCK request indicator. This clashes with the 
valid clock division value 0 that provide the highest fixed clock frequency. 

3. The ft2232_speed_div function return the maximum selectable frequency (30MHz) 
when RTCK is activated. It should return 0. 

4. The ft2232_khz function return ERROR_OK when RTCK is requested even for 
devices lacking RTCK support. It should return ERROR_FAIL so the upper driver layers 
can detect this and try to fallback to a fixed frequency. 

5. FT2232H/FT4232H have a backward compatibility function that divide the clock 
by 5 to get the same frequency range as FT2232D. There is no code that disable 
this functionality. I can not find anything about if this is enabled or disabled by default. 
I think it is safest to actively disable it. 


git-svn-id: svn://svn.berlios.de/openocd/trunk@2591 b42882b7-edfa-0310-969c-e2dbd0fdcd60