Merge pull request #7973 from tannewt/maybe_help_c3

Check usb/jtag for incoming chars too

Author: dhalbert

ports/espressif/supervisor/usb_serial_jtag.c

@@ -101,21 +101,28 @@ bool usb_serial_jtag_connected(void) {
 }
 
 char usb_serial_jtag_read_char(void) {
-    if (ringbuf_num_filled(&ringbuf) == 0) {
+    if (ringbuf_num_filled(&ringbuf) == 0 && !usb_serial_jtag_ll_rxfifo_data_available()) {
         return -1;
     }
-    char c = ringbuf_get(&ringbuf);
+    char c = -1;
+    if (ringbuf_num_filled(&ringbuf) > 0) {
+        c = ringbuf_get(&ringbuf);
+    }
     // Maybe re-enable the recv interrupt if we've emptied the ringbuf.
     if (ringbuf_num_filled(&ringbuf) == 0) {
         usb_serial_jtag_ll_disable_intr_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT);
         _copy_out_of_fifo();
         usb_serial_jtag_ll_ena_intr_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT);
+        // May have only been ctrl-c.
+        if (c == -1 && ringbuf_num_filled(&ringbuf) > 0) {
+            c = ringbuf_get(&ringbuf);
+        }
     }
     return c;
 }
 
 bool usb_serial_jtag_bytes_available(void) {
-    return ringbuf_num_filled(&ringbuf) > 0;
+    return ringbuf_num_filled(&ringbuf) > 0 || usb_serial_jtag_ll_rxfifo_data_available();
 }
 
 void usb_serial_jtag_write(const char *text, uint32_t length) {