stlink: Use callback to increase frequency of trace data sampling

[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 597df6d00e8b26e47f6b9af977ee5a265af76a29..06ec4b7028ef3cf788cca9be452c077fd9684e26 100644 (file)
--- a/src/jtag/drivers/stlink_usb.c
+++ b/src/jtag/drivers/stlink_usb.c
@@ -738,7 +738,7 @@ static int stlink_usb_idcode(void *handle, uint32_t *idcode)
 
        *idcode = le_to_h_u32(h->databuf);
 
-       LOG_DEBUG("IDCODE: 0x%08X", *idcode);
+       LOG_DEBUG("IDCODE: 0x%08" PRIX32, *idcode);
 
        return ERROR_OK;
 }
@@ -830,6 +830,12 @@ static void stlink_usb_trace_read(void *handle)
        }
 }
 
+static int stlink_usb_trace_read_callback(void *handle)
+{
+       stlink_usb_trace_read(handle);
+       return ERROR_OK;
+}
+
 static enum target_state stlink_usb_v2_get_status(void *handle)
 {
        int result;
@@ -1006,8 +1012,10 @@ static void stlink_usb_trace_disable(void *handle)
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_STOP_TRACE_RX;
        res = stlink_usb_xfer(handle, h->databuf, 2);
 
-       if (res == ERROR_OK)
+       if (res == ERROR_OK) {
                h->trace.enabled = false;
+               target_unregister_timer_callback(stlink_usb_trace_read_callback, handle);
+       }
 }
 
 
@@ -1043,7 +1051,15 @@ static int stlink_usb_trace_enable(void *handle)
 
                if (res == ERROR_OK)  {
                        h->trace.enabled = true;
-                       LOG_DEBUG("Tracing: recording at %uHz\n", trace_hz);
+                       LOG_DEBUG("Tracing: recording at %" PRIu32 "Hz\n", trace_hz);
+                       /* We need the trace read function to be called at a
+                        * high-enough frequency to ensure reasonable
+                        * "timeliness" in processing ITM/DWT data.
+                        * TODO: An alternative could be using the asynchronous
+                        * features of the libusb-1.0 API to queue up one or more
+                        * reads in advance and requeue them once they are
+                        * completed. */
+                       target_register_timer_callback(stlink_usb_trace_read_callback, 1, 1, handle);
                }
        } else {
                LOG_ERROR("Tracing is not supported by this version.");
@@ -1065,7 +1081,7 @@ static int stlink_usb_run(void *handle)
                res = stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_DEBUGEN);
 
                /* Try to start tracing, if requested */
-               if (res == ERROR_OK && h->trace.source_hz) {
+               if (res == ERROR_OK && h->trace.source_hz && !h->trace.enabled) {
                        if (stlink_usb_trace_enable(handle) == ERROR_OK)
                                LOG_DEBUG("Tracing: enabled\n");
                        else