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drivers/cmsis-dap: flush read 

Some CMSIS-DAP adapters keep buffered packets over
USB close/open so we need to flush up to 64 old packets
to be sure all buffers are empty.

Flush just after cmsis_dap_open() and in the case of command mismatch.

Change-Id: If21a118639e64d90635b4ecf81013d29a7b9f78d
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/6135
Tested-by: jenkins
Reviewed-by: Adrian M Negreanu <adrian.negreanu@nxp.com>
This commit is contained in:
Tomas Vanek 2021-04-06 18:55:22 +02:00
parent 80970811f4
commit ff755a575e
1 changed files with 19 additions and 0 deletions
src/jtag/drivers
cmsis_dap.c

19
src/jtag/drivers/cmsis_dap.c
View File

@ -281,6 +281,21 @@ static void cmsis_dap_close(struct cmsis_dap *dap)
}
}
static void cmsis_dap_flush_read(struct cmsis_dap *dap)
{
unsigned int i;
/* Some CMSIS-DAP adapters keep buffered packets over
* USB close/open so we need to flush up to 64 old packets
* to be sure all buffers are empty */
for (i = 0; i < 64; i++) {
int retval = dap->backend->read(dap, 10);
if (retval == ERROR_TIMEOUT_REACHED)
break;
}
if (i)
LOG_DEBUG("Flushed %u packets", i);
}
/* Send a message and receive the reply */
static int cmsis_dap_xfer(struct cmsis_dap *dap, int txlen)
{
@ -313,6 +328,8 @@ static int cmsis_dap_xfer(struct cmsis_dap *dap, int txlen)
if (resp[0] != current_cmd) {
LOG_ERROR("CMSIS-DAP command mismatch. Sent 0x%" PRIx8
" received 0x%" PRIx8, current_cmd, resp[0]);
cmsis_dap_flush_read(dap);
return ERROR_FAIL;
}
@ -885,6 +902,8 @@ static int cmsis_dap_init(void)
if (retval != ERROR_OK)
return retval;
cmsis_dap_flush_read(cmsis_dap_handle);
retval = cmsis_dap_get_caps_info();
if (retval != ERROR_OK)
return retval;