On 02/05/2010 08:02 AM, Arnim Läuger wrote: > >>>>> This patch tries to optimize TMS clocks by compacting multiple clocks >>>>> into one FT2232 command. This gives us 6% flash program time reduction. >>>>> And it gives us more performance improvement for gdbproxy when loading >>>>> program via our gnICE and gnICE+ cables. I think this will help other >>>>> JTAG cables based on FT2232(H). >>> >> Another more interesting example is it will optimize >> >> 0x4b 0x00 0x7f 0x4b 0x00 0x7f 0x4b 0x00 0x00 0x4b 0x01 0x7f >> 0x4b 0x00 0x00 0x4b 0x00 0x00 >> >> into >> >> 0x4b 0x06 0x1b > > So your patch compacts multiple clock actions from the todo queue into > an optimized sequence of ft2232 commands. Very interesting, indeed. Such > look-ahead functionality is missing completely in the current driver. > > What is the reason to introduce the URJ_TAP_CABLE_CLOCK_COMPACT action? > Would this mean that all upper layer code needs to be adapted to benefit > from the compaction? It would be nice to implement the look-ahead based > on just the existing URJ_TAP_CABLE_CLOCK action - completely transparent > for the upper layers. Do you see a chance for that? > I introduced URJ_TAP_CABLE_CLOCK_COMPACT because it has different usage of arg.clock.tms. For URJ_TAP_CABLE_CLOCK, arg.clock.tms is only the bit, which will be repeated for arg.clock.n clocks. For URJ_TAP_CABLE_CLOCK_COMPACT, arg.clock.tms is a sequence of TMS signals, which will be set one by one in the next arg.clock.n clocks.
I could change URJ_TAP_CABLE_CLOCK to use the new semantics of arg.clock.tms if we had only ft2232 cables. But I'm not sure we can also change that for usbblaster and generic cables or there is any benefits for those cables. I see URJ_TAP_CABLE_CLOCK_COMPACT as a ft2232 specific action. It is only generated in ft2232 cable drivers and gets handled there. So it will not affect the upper layers. Jie ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ UrJTAG-development mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/urjtag-development
