jtag: usb_blaster: fix initialization regression

[openocd.git] / src / jtag / drivers / usb_blaster / usb_blaster.c

diff --git a/src/jtag/drivers/usb_blaster/usb_blaster.c b/src/jtag/drivers/usb_blaster/usb_blaster.c
index d64a7ea827a3cbe3adff2f09897bc9c13c99022f..82e5537f55f9d7f1c57889c9fa5344fc85a24bbb 100644 (file)
--- a/src/jtag/drivers/usb_blaster/usb_blaster.c
+++ b/src/jtag/drivers/usb_blaster/usb_blaster.c
@@ -756,11 +756,41 @@ static void ublast_usleep(int us)
        jtag_sleep(us);
 }
 
+static void ublast_initial_wipeout(void)
+{
+       static uint8_t tms_reset = 0xff;
+       uint8_t out_value;
+       uint32_t retlen;
+       int i;
+
+       out_value = ublast_build_out(SCAN_OUT);
+       for (i = 0; i < BUF_LEN; i++)
+               info.buf[i] = out_value | ((i % 2) ? TCK : 0);
+
+       /*
+        * Flush USB-Blaster queue fifos
+        *  - empty the write FIFO (128 bytes)
+        *  - empty the read FIFO (384 bytes)
+        */
+       ublast_buf_write(info.buf, BUF_LEN, &retlen);
+       /*
+        * Put JTAG in RESET state (five 1 on TMS)
+        */
+       ublast_tms_seq(&tms_reset, 5);
+       tap_set_state(TAP_RESET);
+}
+
 static int ublast_execute_queue(void)
 {
        struct jtag_command *cmd;
+       static int first_call = 1;
        int ret = ERROR_OK;
 
+       if (first_call) {
+               first_call--;
+               ublast_initial_wipeout();
+       }
+
        for (cmd = jtag_command_queue; ret == ERROR_OK && cmd != NULL;
             cmd = cmd->next) {
                switch (cmd->type) {
@@ -801,14 +831,12 @@ static int ublast_execute_queue(void)
  *
  * Initialize the device :
  *  - open the USB device
- *  - empty the write FIFO (128 bytes)
- *  - empty the read FIFO (384 bytes)
+ *  - pretend it's initialized while actual init is delayed until first jtag command
  *
  * Returns ERROR_OK if USB device found, error if not.
  */
 static int ublast_init(void)
 {
-       static uint8_t tms_reset = 0xff;
        int ret, i;
 
        if (info.lowlevel_name) {
@@ -846,18 +874,13 @@ static int ublast_init(void)
        info.flags |= info.drv->flags;
 
        ret = info.drv->open(info.drv);
-       if (ret == ERROR_OK) {
-               /*
-                * Flush USB-Blaster queue fifos
-                */
-               uint32_t retlen;
-               ublast_buf_write(info.buf, BUF_LEN, &retlen);
-               /*
-                * Put JTAG in RESET state (five 1 on TMS)
-                */
-               ublast_tms_seq(&tms_reset, 5);
-               tap_set_state(TAP_RESET);
-       }
+
+       /*
+        * Let lie here : the TAP is in an unknown state, but the first
+        * execute_queue() will trigger a ublast_initial_wipeout(), which will
+        * put the TAP in RESET.
+        */
+       tap_set_state(TAP_RESET);
        return ret;
 }