Hi all,
I have one general question regarding OpenOCD scans.
What happens when we set some field.in_value = NULL, and in reality
there are some bits that re shifted out on the scan chain ? Are they
just ignored ? Does that pose the problem ?
To give a concrete example, in the mips_ejtag.c we have something like :
/* fastdata 1-bit register */
fields[0].num_bits = 1;
fields[0].out_value = &spracc;
fields[0].in_value = NULL;
/* processor access data register 32 bit */
fields[1].num_bits = 32;
fields[1].out_value = t;
if (write_t)
{
fields[1].in_value = NULL;
buf_set_u32(t, 0, 32, *data);
}
else
{
fields[1].in_value = (uint8_t *) data;
}
So, no values are received (because fields[0].in_value = NULL and
fields[1].in_value = NULL), but in reality MIPS EJTAG shifts out 33
bits (one SPrAcc and 32 bits of DATA) upon this operation.
My question is, in general, could not accepting these bits lead to
some problems or collisions on data lines (or USB bus) ?
BR,
Drasko
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