Jonas Horberg wrote: >> The attached patch add the khz and speed_div functions to >> the parport interface driver. >> >> This enables the jtag_khz command for parport interfaces. >> >> The patch also adds a command named parport_toggling_time >> that tells the parport driver how long (in nanoseconds) it >> takes for the hardware to toggle RTCK. The khz and speed_div >> functions needs this data. The default value is set to >> 1000 ns, perhaps it exist a better typical value. My PC >> have a 1.37 us toggle time. >> > > Comments? > > Configuration scripts with jtag_khz or jtag_rclk fails if these > commands are unsupported. > jtag_speed works just as before. > It seems we do need this, however, the implementation seems wrong.
First, I do not see how RTCK comes into play - AFAIK, the parport interface does not support RTCK, so only TCK frequency should be relevant for jtag_khz. Second, using arbitrary timing values that are measured on one system seems doubly wrong. If we need a specified clock, we need to make sure that the code really produces that clock speed (at most), so the could should auto-adapt to the port timing on the machine it runs on (note that we also do not want overly pessimistic timings - clocking slower than requested degrades performance). cu Michael _______________________________________________ Openocd-development mailing list [email protected] https://lists.berlios.de/mailman/listinfo/openocd-development
