I'm trying to figure out why bitbang fails and ft2232 reportedly
works with arm11.
The attached patch makes a direct transition from shift
to the end state rather than going via pause, which should
line the bitbang driver up more closely with ft2232.
To me this seems like a sensible change and is in line
with the upcoming shortening of transitions.
Comments?
--
Øyvind Harboe
Embedded software and hardware consulting services
http://consulting.zylin.com
Index: src/jtag/bitbang.c
===================================================================
--- src/jtag/bitbang.c (revision 1606)
+++ src/jtag/bitbang.c (working copy)
@@ -84,12 +84,12 @@
}
}
-static void bitbang_state_move(void)
+static void bitbang_state_move(int skip)
{
int i=0, tms=0;
u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
- for (i = 0; i < 7; i++)
+ for (i = skip; i < 7; i++)
{
tms = (tms_scan >> i) & 1;
bitbang_interface->write(0, tms, 0);
@@ -146,7 +146,7 @@
if (tap_get_state() != TAP_IDLE)
{
bitbang_end_state(TAP_IDLE);
- bitbang_state_move();
+ bitbang_state_move(0);
}
/* execute num_cycles */
@@ -160,7 +160,7 @@
/* finish in end_state */
bitbang_end_state(saved_end_state);
if (tap_get_state() != tap_get_end_state())
- bitbang_state_move();
+ bitbang_state_move(0);
}
@@ -191,7 +191,7 @@
else
bitbang_end_state(TAP_DRSHIFT);
- bitbang_state_move();
+ bitbang_state_move(0);
bitbang_end_state(saved_end_state);
}
@@ -227,22 +227,8 @@
}
}
- /* TAP_DRSHIFT & TAP_IRSHIFT are illegal end states, so we always
transition to the pause
- * state which is a legal stable state from which statemove will work.
- *
- * Exit1 -> Pause
- */
- bitbang_interface->write(0, 0, 0);
- bitbang_interface->write(1, 0, 0);
- bitbang_interface->write(CLOCK_IDLE(), 0, 0);
-
- if (ir_scan)
- tap_set_state(TAP_IRPAUSE);
- else
- tap_set_state(TAP_DRPAUSE);
-
if (tap_get_state() != tap_get_end_state())
- bitbang_state_move();
+ bitbang_state_move(1);
}
int bitbang_execute_queue(void)
@@ -310,7 +296,7 @@
#endif
if (cmd->cmd.statemove->end_state !=
TAP_INVALID)
bitbang_end_state(cmd->cmd.statemove->end_state);
- bitbang_state_move();
+ bitbang_state_move(0);
break;
case JTAG_PATHMOVE:
#ifdef _DEBUG_JTAG_IO_
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