On Mon, Apr 4, 2011 at 7:51 PM, Øyvind Harboe <oyvind.har...@zylin.com> wrote: > Any objections to merging 1,2 and 4? > > I think #3 needs more discussion or cool-off. My objection is > that we don't know why this makes things better and it certainly > seems to hit performance hard.
OK, I will open the discussion by question : when do we use jtag_execute_queue() ? Based on the answer from Øyvind I had before, I could conclude that it serves to clock the data back in, while jtag_add_dr_scan() just puts them in the queue to be shifted out at some point. So, if this is correct, then we can avoid using jtag_execute_queue() when we have no data to shift in. But what happens when the TAP will send us bit as a response to FASTDATA, and we are completely ingnoting it ? Will it lead to some collision on the data bus and make ftdi freak out ? Here is EJTAG spec on FASTDATA : Both upload and download accesses are attempted by shifting in a zero SPrAcc value (to request access completion) and shifting out SPrAcc to see if the attempt will be successful (i.e., there was an access pending and a legal Fastdata area address was used). Where do we shift out SPrAcc after the R/W operation (error check) ? I would say nowhere. Can this lead to errors, and can this be an explanation why jtag_execute_queue() is necessary ? BR, Drasko _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
