Severe bug in Pracc code

The function  wait_for_pracc_rw() fails if Pracc bit is 0.
The variable ejtag_ctrl is loaded with the content of the
control register in the first scan.
In the second scan Pracc bit is scanned out as 0, letting
the proccesor go. The result is unpredictable.

All the strange data corruption when scanning at certain
frequencies, or the strange delays needed when entering
or leaving fasdata area are retated to this bug.

Now the code works at any scan frequency, tested up to 15000Khz
and indepently of processor speed, tested at 31.25Khz and 4/8Mhz.

Change-Id: Iedfd81d06d6af4bc738a521f720e42323025b268
Signed-off-by: Salvador Arroyo <sarroyofdez@yahoo.es>
Reviewed-on: http://openocd.zylin.com/769
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

diff --git a/src/target/mips32_pracc.c b/src/target/mips32_pracc.c
index 92b8699e0e21fe93bc1b6e89acaac3633561357b..bae436784af3253a64c7520e2d3b800b6db3b2cf 100644 (file)
--- a/src/target/mips32_pracc.c
+++ b/src/target/mips32_pracc.c
@@ -125,9 +125,9 @@ static int wait_for_pracc_rw(struct mips_ejtag *ejtag_info, uint32_t *ctrl)
 
        /* wait for the PrAcc to become "1" */
        mips_ejtag_set_instr(ejtag_info, EJTAG_INST_CONTROL);
-       ejtag_ctrl = ejtag_info->ejtag_ctrl;
 
        while (1) {
+               ejtag_ctrl = ejtag_info->ejtag_ctrl;
                retval = mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
                if (retval != ERROR_OK)
                        return retval;