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JTAG: fix autoprobe failure. 

Fix bug noted by Øyvind: terminate the IR length autoscan when
the IR is too long, or otherwise broken.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
David Brownell 2009-11-16 16:36:03 -08:00
parent 51862bb98c
commit 7c393679c0
1 changed files with 10 additions and 2 deletions
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12
src/jtag/core.c
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@ -1224,7 +1224,14 @@ static int jtag_validate_ircapture(void)
/* If we're autoprobing, guess IR lengths. They must be at
* least two bits. Guessing will fail if (a) any TAP does
* not conform to the JTAG spec; or (b) when the upper bits
* captured from some conforming TAP are nonzero.
* captured from some conforming TAP are nonzero. Or if
* (c) an IR length is longer than 32 bits -- which is only
* an implementation limit, which could someday be raised.
*
* REVISIT optimization: if there's a *single* TAP we can
* lift restrictions (a) and (b) by scanning a recognizable
* pattern before the all-ones BYPASS. Check for where the
* pattern starts in the result, instead of an 0...01 value.
*
* REVISIT alternative approach: escape to some tcl code
* which could provide more knowledge, based on IDCODE; and
@ -1233,7 +1240,8 @@ static int jtag_validate_ircapture(void)
if (tap->ir_length == 0) {
tap->ir_length = 2;
while ((val = buf_get_u32(ir_test, chain_pos,
tap->ir_length + 1)) == 1) {
tap->ir_length + 1)) == 1
&& tap->ir_length <= 32) {
tap->ir_length++;
}
LOG_WARNING("AUTO %s - use \"... -irlen %d\"",