stlink: Add workaround for intermittent FW info retrieval failure

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

diff --git a/src/jtag/drivers/stlink_usb.c b/src/jtag/drivers/stlink_usb.c
index 1f3fbe2cdc7d7112b7e729084979505e95910902..cccb9ffa0b2fbccd3d83d7aef9240171084aeaf5 100644 (file)
--- a/src/jtag/drivers/stlink_usb.c
+++ b/src/jtag/drivers/stlink_usb.c
@@ -1447,7 +1447,7 @@ static int stlink_usb_close(void *fd)
 /** */
 static int stlink_usb_open(struct hl_interface_param_s *param, void **fd)
 {
-       int err;
+       int err, retry_count = 1;
        struct stlink_usb_handle_s *h;
        enum stlink_jtag_api_version api;
 
@@ -1471,35 +1471,69 @@ static int stlink_usb_open(struct hl_interface_param_s *param, void **fd)
        LOG_DEBUG("transport: %d vid: 0x%04x pid: 0x%04x", param->transport,
                param->vid, param->pid);
 
-       if (jtag_libusb_open(vids, pids, &h->fd) != ERROR_OK) {
-               LOG_ERROR("open failed");
-               goto error_open;
-       }
+       /*
+         On certain host USB configurations(e.g. MacBook Air)
+         STLINKv2 dongle seems to have its FW in a funky state if,
+         after plugging it in, you try to use openocd with it more
+         then once (by launching and closing openocd). In cases like
+         that initial attempt to read the FW info via
+         stlink_usb_version will fail and the device has to be reset
+         in order to become operational.
+        */
+       do {
+               if (jtag_libusb_open(vids, pids, &h->fd) != ERROR_OK) {
+                       LOG_ERROR("open failed");
+                       goto error_open;
+               }
 
-       jtag_libusb_set_configuration(h->fd, 0);
+               jtag_libusb_set_configuration(h->fd, 0);
 
-       if (jtag_libusb_claim_interface(h->fd, 0) != ERROR_OK) {
-               LOG_DEBUG("claim interface failed");
-               goto error_open;
-       }
+               if (jtag_libusb_claim_interface(h->fd, 0) != ERROR_OK) {
+                       LOG_DEBUG("claim interface failed");
+                       goto error_open;
+               }
 
-       /* wrap version for first read */
-       switch (param->pid) {
+               /* wrap version for first read */
+               switch (param->pid) {
                case 0x3744:
                        h->version.stlink = 1;
                        break;
                default:
                        h->version.stlink = 2;
                        break;
-       }
+               }
 
-       /* get the device version */
-       err = stlink_usb_version(h);
+               /* get the device version */
+               err = stlink_usb_version(h);
 
-       if (err != ERROR_OK) {
-               LOG_ERROR("read version failed");
-               goto error_open;
-       }
+               if (err == ERROR_OK) {
+                       break;
+               } else if (h->version.stlink == 1 ||
+                          retry_count == 0) {
+                       LOG_ERROR("read version failed");
+                       goto error_open;
+               } else {
+                       err = jtag_libusb_release_interface(h->fd, 0);
+                       if (err != ERROR_OK) {
+                               LOG_ERROR("release interface failed");
+                               goto error_open;
+                       }
+
+                       err = jtag_libusb_reset_device(h->fd);
+                       if (err != ERROR_OK) {
+                               LOG_ERROR("reset device failed");
+                               goto error_open;
+                       }
+
+                       jtag_libusb_close(h->fd);
+                       /*
+                         Give the device one second to settle down and
+                         reenumerate.
+                        */
+                       usleep(1 * 1000 * 1000);
+                       retry_count--;
+               }
+       } while (1);
 
        /* compare usb vid/pid */
        if ((param->vid != h->vid) || (param->pid != h->pid))